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Journal articles on the topic 'Stereochemistry. Steroids'

Author: Grafiati

Published: 4 June 2021

Last updated: 17 February 2022

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1

Al-Fouti, Khaled, and James R. Hanson. "The Hydroboration of Some Steroidal Hydroxymethylene Derivatives." Journal of Chemical Research 2003, no. 1 (2003): 6–7. http://dx.doi.org/10.3184/030823403103172931.

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The regio- and stereochemistry of the hydroboration of some methoxymethylene steroids and hydroxymethylene (β-formyl) steroidal ketones and the oxidation of the adducts to form the corresponding hydroxymethyl steroids, are described.

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2

WINTERFELDT, E. "ChemInform Abstract: Steroids and Stereochemistry." ChemInform 25, no. 40 (2010): no. http://dx.doi.org/10.1002/chin.199440272.

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3

Kicha, Alla A., Anatoly I. Kalinovsky, Alexander S. Antonov, et al. "Determination of C-23 Configuration in (20R)-23-Hydroxycholestane Side Chain of Steroid Compounds by 1H and 13C NMR Spectroscopy." Natural Product Communications 8, no. 9 (2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800908.

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Epimeric (20 R,23 R)- and (20 R,23 S)-23-hydroxycholestane steroids were synthesized. Their structures were elucidated by extensive 1H and 13C NMR spectroscopy and application of the Mosher's method. All proton and carbon signals of the side chains were assigned. Based on these assignments spectral data allow the determination of the C-23 stereochemistry of (20 R)-23-hydroxycholestane side chains of the new natural steroids by comparison with spectra of the obtained model compounds. As a result, the C-23 configuration of two steroid compounds from the starfishes Lethasterias nanimensis chelife

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4

Ermolovich, Yu V., V. N. Zhabinskii, and V. A. Khripach. "Formation of the steroidal C-25 chiral center via the asymmetric alkylation methodology." Organic & Biomolecular Chemistry 13, no. 3 (2015): 776–82. http://dx.doi.org/10.1039/c4ob02123a.

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A novel approach for the preparation of steroids containing a chiral center at C-25 is reported. The key stereochemistry inducing step was asymmetric alkylation of pseudoephenamine amides of steroidal C-26 acids. The developed methodology was successfully applied to the synthesis of (25R)- and (25S)-cholestenoic acids as well as (25R)- and (25S)-26-hydroxy brassinolides.

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5

Paryzek, Zdzislaw, and Krzysztof Blaszczyk. "Spiro steroids via the Barbier–Grignard reaction of steroidal ketones with allyl bromide and magnesium." Canadian Journal of Chemistry 65, no. 1 (1987): 229–33. http://dx.doi.org/10.1139/v87-037.

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Barbier–Grignard reaction of 3- and 17-steroidal ketones gave excellent yields of the allyl steroids 1 + 2 and 15. These were transformed into a mixture of 1,3- and 1,4-diols by hydroboration–oxidation. The diols 3,5, and 18 were used for the preparation of spirolactones and spiroethers. Thus, the Barbier–Grignard allylation–hydroboration–cyclization sequence proved to be an effective method for the spiroannelation of steroidal ketones. It was also shown that an earlier assignment of the stereochemistry of the diols 3 and 5 was erroneous.

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6

Kolekar, Supriya Murarji, B. U. Jain, and M. S. Kondawarkar. "A Review on Steroids and Terpenoids (Stereochemistry, Structural Elucidation, Isolation of Steroids and Terpenoids)." Research Journal of Pharmaceutical Dosage Forms and Technology 11, no. 2 (2019): 126. http://dx.doi.org/10.5958/0975-4377.2019.00020.x.

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7

Zaretskii, Z. V. I., J. M. Curtis, D. Ghosh, and A. G. Brenton. "Mass spectrometry of metastable ions and stereochemistry of steroids." International Journal of Mass Spectrometry and Ion Processes 86 (December 1988): 121–36. http://dx.doi.org/10.1016/0168-1176(88)80059-4.

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8

Mander, Lewis N. "Charles William Shoppee. 4 February 1904 – 20 October 1994." Biographical Memoirs of Fellows of the Royal Society 49 (January 2003): 495–507. http://dx.doi.org/10.1098/rsbm.2003.0029.

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Charles Shoppee was a major figure in research into the steroid family of organic compounds. After an extensive grounding in mechanistic organic chemistry with such major figures as Sir Jocelyn Thorpe FRS at Imperial College and Sir Christopher Ingold FRS at the University of Leeds, Shoppee spent the war years in Basel working with Tadeus Reichstein (ForMemRS 1952). There he began to apply reaction mechanistic concepts to the reactions of natural products, particularly steroids, in which he was in the vanguard of a huge and widespread activity prompted, in part, by the pharmaceutical industry'

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9

Huszcza, Ewa, Jadwiga Dmochowska-Gładysz, and Agnieszka Bartmańska. "Transformations of Steroids by Beauveria bassiana." Zeitschrift für Naturforschung C 60, no. 1-2 (2005): 103–8. http://dx.doi.org/10.1515/znc-2005-1-219.

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The course of transformations of testosterone and its derivatives, including compounds with an additional C1,C2 double bond and/or a 17α-methyl group, a 17β-acetyl group or without a 19-methyl group, by a Beauveria bassiana culture was investigated. The fungi promoted hydroxylation of these compounds at position 11α, oxidation of the 17β-hydroxyl group, reduction of the C1,C2 or C4,C5 double bonds and degradation of the progesterone side-chain, leading to testosterone. The structure of 4-ene-3-oxo-steroids had no influence on regio- and stereochemistry of hydroxylation. In a similar manner, de

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10

Zaretskii, Z. V. I., D. Ghosh, A. G. Brenton, and J. H. Beynon. "Translational energy release and stereochemistry of steroids. 14. Epimeric dihydroxy steroids of the androstane series." Rapid Communications in Mass Spectrometry 3, no. 10 (1989): 329–34. http://dx.doi.org/10.1002/rcm.1290031002.

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11

Hanson, James R., Nicolas Terry та Cavit Uyanik. "The Stereochemistry of Epoxidation of Δ5-Steroids with Sodium Perborate and Potassium Permanganate†". Journal of Chemical Research, № 1 (1998): 50–51. http://dx.doi.org/10.1039/a706111k.

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12

Zaretskii, Z. V. I., D. Ghosh, A. G. Brenton, and J. H. Beynon. "Translational energy release and stereochemistry of steroids 15. Reaction conformations of metastable molecular ions in stereoisomers of 3-hydroxy steroids." Rapid Communications in Mass Spectrometry 4, no. 2 (1990): 44–51. http://dx.doi.org/10.1002/rcm.1290040203.

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13

Jin, Yi, A. Clementina Mesaros, Ian A. Blair та Trevor M. Penning. "Stereospecific reduction of 5β-reduced steroids by human ketosteroid reductases of the AKR (aldo-keto reductase) superfamily: role of AKR1C1–AKR1C4 in the metabolism of testosterone and progesterone via the 5β-reductase pathway". Biochemical Journal 437, № 1 (2011): 53–61. http://dx.doi.org/10.1042/bj20101804.

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Active sex hormones such as testosterone and progesterone are metabolized to tetrahydrosteroids in the liver to terminate hormone action. One main metabolic pathway, the 5β-pathway, involves 5β-steroid reductase (AKR1D1, where AKR refers to the aldo-keto reductase superfamily), which catalyses the reduction of the 4-ene structure, and ketosteroid reductases (AKR1C1–AKR1C4), which catalyse the subsequent reduction of the 3-oxo group. The activities of the four human AKR1C enzymes on 5β-dihydrotestosterone, 5β-pregnane-3,20-dione and 20α-hydroxy-5β-pregnan-3-one, the intermediate 5β-dihydrostero

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14

HANSON, J. R., N. TERRY та C. UYANIK. "ChemInform Abstract: The Stereochemistry of Epoxidation of Δ5-Steroids with Sodium Perborate and Potassium Permanganate." ChemInform 30, № 6 (2010): no. http://dx.doi.org/10.1002/chin.199906167.

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15

Hendry, Lawrence B., Thomas G. Muldoon, and Virendra B. Mahesh. "The metabolic pathways for hormonal steroids appear to be reflected in the stereochemistry of DNA." Journal of Steroid Biochemistry and Molecular Biology 42, no. 7 (1992): 659–70. http://dx.doi.org/10.1016/0960-0760(92)90106-s.

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16

Holland, Herbert L., Frances M. Brown, P. Chinna Chenchaiah, and J. Appa Rao. "Hydroxylation of prostanoids by fungi. Synthesis of (−)-15-deoxy-19-(R)-hydroxy-PGE1 and (−)-15-deoxy-18-(S)-hydroxy-PGE1." Canadian Journal of Chemistry 68, no. 2 (1990): 282–93. http://dx.doi.org/10.1139/v90-039.

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A series of racemic substituted cyclopentanones, with alkyl groups corresponding to the upper prostanoid side chain and (or) the lower prostanoid side chain without the C-15 alcohol, has been synthesized. Using a steroid template for the prostanoid molecule as a basis for selection, fungi capable of hydroxylating steroids have been used to biotransform the prostanoid substrates. The predominant products were hydroxylated at the prostanoid C-18 and C-19 positions. The hydroxylations were enantioselective, with excesses in the range 10–60%, and in most cases the predominant configuration corresp

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17

Ndibwami, Alexis, Serge Lamothe, Daniel Guay, et al. "Transannular Diels–Alder reactions on 14-membered macrocyclic trienes. Part I: stereoselective syntheses of the macrocyclic trienes precursors." Canadian Journal of Chemistry 71, no. 5 (1993): 695–713. http://dx.doi.org/10.1139/v93-094.

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Transannular Diels–Alder reactions on 14-membered macrocycles containing properly located diene and methyl-substituted dienophile units lead to A.B.C.[6.6.6] tricycles related to steroids. To study the influence of the olefin and diene geometry on the stereochemical outcome of the Diels–Alder reaction it was necessary to prepare macrocyclic trienes of well-defined stereochemistry. Eight different types of macrocyclic trienes might be obtained by the coupling of appropriate dienophiles and dienes, namely, TTC, TTT, TCC, TCT, CTC, CTT, CCC, and CCT. In this paper (first in a series of two), the

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18

Liu, Xiang-Hong, Xiao-Zhen Tang, Feng-Ping Miao, and Nai-Yun Ji. "A New Pyrrolidine Derivative and Steroids from an Algicolous Gibberella zeae Strain." Natural Product Communications 6, no. 9 (2011): 1934578X1100600. http://dx.doi.org/10.1177/1934578x1100600908.

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A new pyrrolidine derivative, 3-hydroxy-5-(hydroxymethyl)-4-(4′-hydroxyphenoxy)pyrrolidin-2-one (1), and eight known steroids, (22 E,24 R)-7β,8β-epoxy-3β,5α,9α-trihydroxyergosta-22-en-6-one (2, a reassigned structure of (22 E,24 R)-5α,6α-epoxy-3β,8β,14α-trihydroxyergosta-22-en-7-one), (22 E,24 R)-3β,5α,9α-trihydroxyergosta-7,22-dien-6-one (3), (22 E,24 R)-3β,5α-dihydroxyergosta-7,22-dien-6-one (4), (22 E,24 R)-ergosta-7,22-dien-3β,5α,6β-triol (5), (22 E,24 R)-ergosta-5,22-dien-3β-ol (6), (22 E,24 R)-5α,8α-epidioxyergosta-6,22-dien-3β-ol (7), (22 E,24 R)-5α,8α-epidioxyergosta-6,9(11),22-trien-3

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19

Holland, Herbert L., Ronald W. Ninniss, and Frances M. Brown. "Stereochemistry of hydrogen loss during C-21 dehydroxylation of tetrahydrodeoxycorticosterone by Eubacteriumlentum." Canadian Journal of Chemistry 67, no. 10 (1989): 1590–95. http://dx.doi.org/10.1139/v89-242.

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The loss of hydrogen from the C-21 position of 5β-pregnane-3α,21-diol-20-one (tetrahydrodeoxycorticosterone, THDOC) during reductive removal of the 21-hydroxy group by the anaerobic bacterium Eubacteriumlentum has been shown to be selective for the pro-S position by the use of THDOC labelled with deuterium at the C-21 pro-S and C-21 pro-R positions. The labelled substrates were obtained by using the bacterium Clostridiumparaputrificum to reduce chemically prepared C-21 labelled samples of pregn-4-en-21-ol-3,20-dione (deoxycorticosterone, DOC) at C-3 and C-4 (5). The stereochemistry of deuteriu

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20

Matulja, Dario, Karlo Wittine, Nela Malatesti, et al. "Marine Natural Products with High Anticancer Activities." Current Medicinal Chemistry 27, no. 8 (2020): 1243–307. http://dx.doi.org/10.2174/0929867327666200113154115.

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This review covers recent literature from 2012-2019 concerning 170 marine natural products and their semisynthetic analogues with strong anticancer biological activities. Reports that shed light on cellular and molecular mechanisms and biological functions of these compounds, thus advancing the understanding in cancer biology are also included. Biosynthetic studies and total syntheses, which have provided access to derivatives and have contributed to the proper structure or stereochemistry elucidation or revision are mentioned. The natural compounds isolated from marine organisms are divided i

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21

van Hes, R., U. K. Pandit, and H. O. Huisman. "Heterocyclic Steroids. Part XI 1-Hydroxy-1-vinylquinolizidine - its synthesis, stereochemistry and attempted conversion to 5-azasteroids." Recueil des Travaux Chimiques des Pays-Bas 86, no. 11 (2010): 1255–62. http://dx.doi.org/10.1002/recl.19670861112.

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22

Zaretskii, Z. V. I., J. M. Curtis, A. G. Brenton, J. H. Beynon та Carl Djerassi. "Translational energy release and stereochemistry of steroids. VIII-The mechanism of the elimination of water from metastable ions in epimeric 3-hydroxy steroids of the 5α-series". Organic Mass Spectrometry 23, № 6 (1988): 453–59. http://dx.doi.org/10.1002/oms.1210230605.

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23

Zaretskii, Z. V. I., J. M. Curtis, A. G. Brenton, J. H. Beynon та Carl Djerassi. "Translational energy release and stereochemistry of steroids. IX-The mechanism of the elimination of water from metastable ions in epimeric 3-hydroxy steroids of the 5β-series". Organic Mass Spectrometry 23, № 6 (1988): 460–68. http://dx.doi.org/10.1002/oms.1210230606.

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24

Zaretskii, Z. V. I., Z. Kustanovich, E. E. Kingston, et al. "Translational energy release and stereochemistry of steroids 6—Contribution of the 18- and 19-methyl groups to the translational energy release for the angular methyl loss in unsaturated steroids." Organic Mass Spectrometry 20, no. 7 (1985): 471–75. http://dx.doi.org/10.1002/oms.1210200709.

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25

Zaretskii, Z. V. I., Z. Kustanovich, E. E. Kingston, J. H. Beynon, Carl Djerassi та L. Tökes. "Translational energy release and stereochemistry of steroids. VII—the loss of angular methyl groups after the dehydration of molecular ions of cholesterol and related C(5)-unsaturated 3β-hydroxy steroids". Organic Mass Spectrometry 21, № 3 (1986): 125–30. http://dx.doi.org/10.1002/oms.1210210306.

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26

Zaretskii, Z. V. I., J. M. Curtis, A. G. Brenton, J. H. Beynon та U. P. Schlunegger. "Translational energy release and stereochemistry of steroids. XII. The differences in the origin ofm/z 124 and 163 key ions in epimeric 11-hydroxy steroids of the Δ4-3-keto series". Rapid Communications in Mass Spectrometry 1, № 7-8 (1987): 117–19. http://dx.doi.org/10.1002/rcm.1290010708.

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27

Xu, Yao-Chang, Andrew L. Roughton, Raymond Plante, Solo Goldstein, and Pierre Deslongchamps. "Stereocontrolled construction of 1,7-dimethyl A.B.C.[6.6.6] tricycles. Part I. Transannular Diels–Alder reactions of 14-membered macrocycles containing trans-dienophiles." Canadian Journal of Chemistry 71, no. 8 (1993): 1152–68. http://dx.doi.org/10.1139/v93-152.

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Transannular Diels–Alder reactions of 14-membered macrocyclic trienes possessing a methyl substituent on both the diene and dienophile moiety have been investigated. Macrocyclic structures 1a, 1b, and 1c having cis-trans-trans (CTT), trans-cis-trans (TCT), and trans-trans-trans (TTT) geometries could be stereoselectively constructed by coupling appropriately functionalized dienes 5 and dienophile 4 following an intramolecular displacement of an allylic halide by the anion of an appropriately located dimethyl malonate unit. The transannular Diels–Alder reaction performed on 1a led to a mixture

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28

Zaretskii, Z. V. I., J. M. Curtis, A. G. Brenton та J. H. Beynon. "Translational energy release and stereochemistry of steroids. XI—Determination of the configuration of α,β-unsaturated 3-keto steroid alcohols with the hydroxyl group in rings C and D". Organic Mass Spectrometry 23, № 7 (1988): 511–16. http://dx.doi.org/10.1002/oms.1210230703.

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29

Zaretskii, Z. V. I., J. M. Curtis, A. G. Brenton, J. H. Beynon, and U. P. Schlunegger. "Translational energy release and stereochemistry of steroids. X. The Effect of the 5,6-double bond on the elimination of angular methyls and water from metastable molecular ions of epimeric steroid alcohols." Rapid Communications in Mass Spectrometry 1, no. 3 (1987): 45–47. http://dx.doi.org/10.1002/rcm.1290010305.

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30

Yoshida, Tatsuya, Rinako Ujiie, Alan H. Savitzky, et al. "Dramatic dietary shift maintains sequestered toxins in chemically defended snakes." Proceedings of the National Academy of Sciences 117, no. 11 (2020): 5964–69. http://dx.doi.org/10.1073/pnas.1919065117.

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Unlike other snakes, most species ofRhabdophispossess glands in their dorsal skin, sometimes limited to the neck, known as nucho-dorsal and nuchal glands, respectively. Those glands contain powerful cardiotonic steroids known as bufadienolides, which can be deployed as a defense against predators. Bufadienolides otherwise occur only in toads (Bufonidae) and some fireflies (Lampyrinae), which are known or believed to synthesize the toxins. The ancestral diet ofRhabdophisconsists of anuran amphibians, and we have shown previously that the bufadienolide toxins of frog-eating species are sequester

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31

Holland, Herbert L., Sudalaiyandi Kumaresan, and Gingipalli Lakshmaiah. "Synthesis of steroidal [4,6-b,c]-benzothiazepines, a new class of aromatase inhibitor." Canadian Journal of Chemistry 73, no. 12 (1995): 2185–89. http://dx.doi.org/10.1139/v95-271.

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Several steroidal [4,6-b,c]benzothiazepines have been prepared via base-catalyzed Michael addition of 2-aminothiophenol to 3β,17β-diacetoxyandrost-4-en-6-one. The product of this reaction has the 4β,5α stereochemistry, but cyclizes to a benzothiazepine with the steroidal 4β,5β configuration, confirmed by X-ray crystallographic analysis. 2-Aminothiophenol reacts with 3β,17β-diacetoxyandrost-4-en-6-one under acidic conditions to give a steroidal 6-spiro-benzothiazole. An androst-4-ene-3,17-dione-based [4,6]benzothiazepine has been shown to be a moderate competitive inhibitor of the human placent

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32

Horinouchi, Masae, Toshiaki Hayashi, Hiroyuki Koshino, Michal Malon, Takako Yamamoto, and Toshiaki Kudo. "Identification of Genes Involved in Inversion of Stereochemistry of a C-12 Hydroxyl Group in the Catabolism of Cholic Acid by Comamonas testosteroni TA441." Journal of Bacteriology 190, no. 16 (2008): 5545–54. http://dx.doi.org/10.1128/jb.01080-07.

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ABSTRACT Comamonas testosteroni TA441 degrades steroids such as testosterone via aromatization of the A ring, followed by meta-cleavage of the ring. In the DNA region upstream of the meta-cleavage enzyme gene tesB, two genes required during cholic acid degradation for the inversion of an α-oriented hydroxyl group on C-12 were identified. A dehydrogenase, SteA, converts 7α,12α-dihydroxyandrosta-1,4-diene-3,17-dione to 7α-hydroxyandrosta-1,4-diene-3,12,17-trione, and a hydrogenase, SteB, converts the latter to 7α,12β-dihydroxyandrosta-1,4-diene-3,17-dione. Both enzymes are members of the short-c

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33

Matile, Stefan. "Organic Chemistry for First Year Medical Students: Addressing the 'Grand Public'." CHIMIA International Journal for Chemistry 75, no. 1 (2021): 27–32. http://dx.doi.org/10.2533/chimia.2021.27.

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Experiences from 20 years of teaching organic chemistry at the Medical School of the University of Geneva are recollected. Emphasis is on the question how to address a large audience without particular passion for chemistry. The key lesson learned is to offer a substantial justification for every topic right at the beginning, before the basics are covered. For instance, the course opens with vancomycin resistance, achieved by changing one functional group, even one atom into another, and introductory topics are then developed literally on the structure of a beautifully complex natural product

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34

Kamernitskii, A. V., I. G. Reshetova та S. V. Chernov. "Transformed steroids. 164. Influence of 12-substituent on stereochemistry of epoxidation of Δ8(14)-bond and direction of opening of the 8,14-oxide ring in 5β-cholanic acids". Bulletin of the Academy of Sciences of the USSR Division of Chemical Science 36, № 7 (1987): 1513–17. http://dx.doi.org/10.1007/bf01557537.

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35

Al-Fouti, Khaled, James R. Hanson, and Peter B. Hitchcock. "The Hydroboration of Steroidal Vinyl Halides." Journal of Chemical Research 2002, no. 12 (2002): 614–15. http://dx.doi.org/10.3184/030823402103170989.

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The hydroboration of 2- and 3-dibromo and dichioromethylene 5α-androstanes has been shown to afford the 2β-and 3α- and 3β-hydroxymethyl-5α-androstanes respectively; a 3-chloro substituent changed both the regio- and stereochemistry of the hydroboration of a 3,5-diene.

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36

Rochfort, SJ, RW Gable, and RJ Capon. "Mycalone: a New Steroidal Lactone From a Southern Australian Marine Sponge, Mycale sp." Australian Journal of Chemistry 49, no. 6 (1996): 715. http://dx.doi.org/10.1071/ch9960715.

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Mycalone (1), a new steroid incorporating a novel six- membered lactone side chain, has been isolated fram a southern Australian marine sponge, Mycale sp. The gross structure for mycalone (1) was secured by spectroscopic analysis, and the stereochemistry established by a single-crystal X-ray structure determination.

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37

Xu, W., I. Alroy, L. F. Freedman, and P. B. Sigler. "Stereochemistry of Specific Steroid Receptor-DNA Interactions." Cold Spring Harbor Symposia on Quantitative Biology 58 (January 1, 1993): 133–39. http://dx.doi.org/10.1101/sqb.1993.058.01.017.

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38

Hanson, James R., Peter B. Hitchcock, and Ismail Kiran. "The Stereochemistry of Epoxidation of Steroidal 4,6-Dienes." Journal of Chemical Research 23, no. 3 (1999): 198–99. http://dx.doi.org/10.1177/174751989902300314.

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The epoxidation of some androsta-4,6-dienes with m-chloroperbenzoic acid has been shown to give the 4β, 5β; 6α, 7α-diepoxides, the stereochemistry can be rationalized in terms of the directing effect of one epoxide on the facial selectivity of the second epoxidation.

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39

Paryzek, Zdzislaw, and Krzysztof Blaszczyk. "Steroidal cyclobutanones, I. Synthesis and stereochemistry of steroidal spirocyclobutanones." Liebigs Annalen der Chemie 1990, no. 7 (1990): 665–70. http://dx.doi.org/10.1002/jlac.1990199001126.

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40

Challinor, Victoria L., and James J. De Voss. "Assignment of stereochemistry in open-chain steroidal saponins." Pure and Applied Chemistry 84, no. 6 (2012): 1469–78. http://dx.doi.org/10.1351/pac-con-11-09-12.

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The major phytochemical constituents of the widely used medicinal herb Chamaelirium luteum (“false unicorn”) are open-chain cholesterol-derived steroidal saponins. These are unusual in lacking the extra ring(s) derived from the steroidal side chain that are characteristic of the more commonly isolated furostanol and spirostanol saponins. The structures of the major steroidal saponins of C. luteum were determined using a combination of multistage mass spectrometry (MSn), 1D and 2D NMR experiments, and chemical degradation. The flexible nature of the steroidal side chain in these saponins necess

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41

Challinor, Victoria L., David M. Smith, and James J. De Voss. "Steroidal Saponins Isolated from an Australian Yam Dioscorea sp." Australian Journal of Chemistry 64, no. 5 (2011): 545. http://dx.doi.org/10.1071/ch11056.

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Phytochemical characterization of the rhizome of an Australian species of Dioscorea, acquired as Dioscorea transversa R Br. but botanically identified as Dioscorea sp., led to the isolation of two steroidal saponins. The major constituent 1β-hydroxyprotogracillin (1) was previously unknown while the minor one was identified as protogracillin (2). The structure and stereochemistry of 1 were elucidated using a combination of MS studies, 1D and 2D NMR experiments and chemical degradation.

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42

Uyanik, Cavit, James R. Hanson, and Peter B. Hitchcock. "The Stereochemistry of the 1,2-Addition of Grignard Reagents to Some Steroidal Unsaturated Ketones." Journal of Chemical Research 2003, no. 8 (2003): 474–76. http://dx.doi.org/10.3184/030823403103174588.

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The stereochemistry of 3β,17β-dihydroxy-3α-ethylandrost-4-ene, 3α,17β-dihydroxy-3β-methylestr-4-ene and 3β-acetoxy-7α,17β-dihydroxy-7β-methylandrost-5-ene, which were obtained by Grignard reactions from the corresponding αβ-unsaturated ketones, have been established by X-ray crystallography.

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Hanson, James R., Peter B. Hitchcock, and Ismail Kiran. "The Stereochemistry of Epoxidation of Steroidal 4,6-Dienes." Journal of Chemical Research, no. 3 (1999): 198–99. http://dx.doi.org/10.1039/a809182j.

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44

Dembitsky, V. M., G. A. Tolstikov та M. Srebnik. "Boranes in Organic Chemistry 2. β-Aminoalkyl- and β-sulfanylalkylboranes in organic synthesis". Eurasian Chemico-Technological Journal 4, № 3 (2017): 153. http://dx.doi.org/10.18321/ectj528.

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<p>Problems on using of β-aminoalkyl- and β-sulfanylalkylboranes in organic synthesis are considered in this review. The synthesis of boron containing a-aminoacids by Curtius rearrangement draws attention. The use of β-aminoalkylboranes available by enamine hydroboration are described. Examples of enamine desamination with the formation of alkenes, aminoalcohols and their transformations into allylic alcohol are presented. These conversions have been carried out on steroids and nitrogen containing heterocyclic compounds. The dihydroboration of N-vinyl-carbamate and N-vinyl-urea have been

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45

Challinor, Victoria L., David M. Smith, and James J. De Voss. "Corrigendum to: Steroidal Saponins Isolated from an Australian Yam Dioscorea sp." Australian Journal of Chemistry 64, no. 11 (2011): 1540. http://dx.doi.org/10.1071/ch11056_co.

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Phytochemical characterization of the rhizome of an Australian species of Dioscorea, acquired as Dioscorea transversa R Br. but botanically identified as Dioscorea sp., led to the isolation of two steroidal saponins. The major constituent 1?-hydroxyprotogracillin (1) was previously unknown while the minor one was identified as protogracillin (2). The structure and stereochemistry of 1 were elucidated using a combination of MS studies, 1D and 2D NMR experiments and chemical degradation.

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46

Guo, Wenqiang, Wenjie Liu, Feng Xiao, et al. "New Cytotoxic Steroid Produced by the Soil-Derived Fungus Aspergillus flavus JDW-1." Natural Product Communications 14, no. 5 (2019): 1934578X1985037. http://dx.doi.org/10.1177/1934578x19850376.

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One new steroid 1, together with seven known compounds 2 to 8, were discovered in the extract of a soil-derived fungus Aspergillus flavus JDW-1. The structure, including the absolute stereochemistry of new compound 1, was established by interpretation of extensive nuclear magnetic resonance spectroscopic data and further confirmed by X-ray crystallographic analysis. The cytotoxicity of 1 against the A-549, Hela, HCT-116, MGC-803, and HO-8910 cell lines was evaluated, which showed cytotoxicity with the half-maximal inhibitory concentration (IC50) values as 5.00 to 22.38 μM. Compounds 2 to 8 exh

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47

Lannang, Alain Meli, Shazia Anjum, Jean Gustave Tangmouo, Karsten Krohn, and M. Iqbal Choudhary. "Conessine isolated from Holarrhena floribunda." Acta Crystallographica Section E Structure Reports Online 63, no. 11 (2007): o4398. http://dx.doi.org/10.1107/s1600536807051215.

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The title compound, C24H40N2, has been isolated from Holarrhena floribunda G. Don. (Apocynaceae). The compound has a pentacyclic steroidal nucleus; the ring junctions share the same stereochemistry reported for this class of compounds. Of the three six-membered rings, rings A and C adopt a chair-like and ring B forms a half-chair-like conformation. The cyclopentane ring D shows a half-chair conformation and the methylpyrrolidine ring E adopts an envelope conformation. The dimethylamino substituent in ring A is equatorially oriented.

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48

Hanson, James R., Peter B. Hitchcock, and Ismail Kiran. "ChemInform Abstract: The Stereochemistry of Epoxidation of Steroidal 4,6-Dienes." ChemInform 30, no. 34 (2010): no. http://dx.doi.org/10.1002/chin.199934212.

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Challinor, Victoria L., and James J. De Voss. "ChemInform Abstract: Assignment of Stereochemistry in Open-Chain Steroidal Saponins." ChemInform 44, no. 7 (2013): no. http://dx.doi.org/10.1002/chin.201307220.

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Carlson, Heather A., and William L. Jorgensen. "Investigations into the stereochemistry of cyclophane-steroid complexes via Monte Carlo simulations." Tetrahedron 51, no. 2 (1995): 449–72. http://dx.doi.org/10.1016/0040-4020(94)00908-d.

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