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Journal articles on the topic 'B ring system'

Author: Grafiati

Published: 5 June 2025

Last updated: 1 August 2025

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1

Gopinath, S., K. Sethusankar, Helen Stoeckli-Evans, Muhamad Rafiq, and Arasambattu K. Mohanakrishnan. "Crystal structure of 6-(p-tolyl)benzo[b]naphtho[2,3-d]thiophene and of an orthorhombic polymorph of 7-phenylanthra[2,3-b]benzo[d]thiophene." Acta Crystallographica Section E Crystallographic Communications 72, no. 9 (2016): 1310–14. http://dx.doi.org/10.1107/s2056989016012937.

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The title compounds, C23H16S, (I), and C26H16S, (II), are benzothiophene derivatives in which the benzothiophene moiety is fused with a naphthalene ring system in (I), and with an anthracene ring system in (II). In (I), the mean plane of the benzothiophene ring system makes a dihedral angle of 2.28 (6)° with the naphthalene ring system, and a dihedral angle of 1.28 (6)° with the anthracene ring system in (II), showing that the fused units are essentially planar. In (I), the 4-methylbenzene ring substituent makes a dihedral angle of 71.40 (9)° with the naphthalene ring system, while the phenyl

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2

Nicolaou, K. C., C. K. Hwang, and M. E. Duggan. "Synthesis of the brevetoxin B IJK ring system." Journal of the American Chemical Society 111, no. 17 (1989): 6682–90. http://dx.doi.org/10.1021/ja00199a031.

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3

Olesen, Preben H., John B. Hansen, and Mogens Engelstoft. "Thieno[2,3-b]indole. The unsubstituted ring system." Journal of Heterocyclic Chemistry 32, no. 5 (1995): 1641–42. http://dx.doi.org/10.1002/jhet.5570320540.

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4

Feng, Fei, and Akio Murai. "Synthesis of the A- and B-Ring System of Hemibrevetoxin-B." Chemistry Letters 24, no. 1 (1995): 23–24. http://dx.doi.org/10.1246/cl.1995.23.

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5

Suarato, Antonino, Francesco Angelucci, and Cristina Geroni. "Ring-B Modified Anthracyclines." Current Pharmaceutical Design 5, no. 3 (1999): 217–27. http://dx.doi.org/10.2174/1381612805666230109215627.

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One of the most investigated classes of antitumor drugs is represented by anthracyclines. Over thirty years since the original discovery of daunorubicin and doxorubicin thousands of anthracycline analogues have been synthesized and tested to identify compounds superior to the parent drugs in terms of increased therapeutic effectiveness, reduced toxicity or both. Previous structure-activity studies had shown that minor modifications of the anthracycline structure can result not only in active agents, but, more importantly, analogues with reduced cardiotoxicity and activity on multi drug resista

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6

McGowan, Craig A., Ann-Kathrin Schmieder, Lee Roberts, and Michael F. Greaney. "Synthesis of the guanacastepene A–B hydrazulene ring system through photochemical ring transposition." Org. Biomol. Chem. 5, no. 10 (2007): 1522–24. http://dx.doi.org/10.1039/b704865c.

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7

Aran, Vicente J., Nazario Martin, Carlos Seoane, Jose L. Soto, Juliana Sanz-Aparicio, and Feliciana Florencio. "A novel ring system: 6a-aminofuro[2,3-b]furans." Journal of Organic Chemistry 53, no. 22 (1988): 5341–43. http://dx.doi.org/10.1021/jo00257a025.

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8

Matsukura, Hiroko, Masamichi Morimoto, and Tadashi Nakata. "Stereoselective Synthesis of ABC-Ring System of Hemibrevetoxin B." Chemistry Letters 25, no. 6 (1996): 487–88. http://dx.doi.org/10.1246/cl.1996.487.

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9

Nicolaou, K. C., M. E. Duggan, and C. K. Hwang. "Synthesis of the ABC ring system of brevetoxin B." Journal of the American Chemical Society 111, no. 17 (1989): 6666–75. http://dx.doi.org/10.1021/ja00199a029.

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10

Nicolaou, K. C., M. E. Duggan, and C. K. Hwang. "Synthesis of the FG ring system of brevetoxin B." Journal of the American Chemical Society 111, no. 17 (1989): 6676–82. http://dx.doi.org/10.1021/ja00199a030.

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11

He´nin, Jacques, Joseph Vercauteren, Catherine Mangenot, Be´atrice He´nin, Jean Marc Nuzillard, and Jean Guilhem. "New entries into theindolizino[8,7-b]indole ring system." Tetrahedron 55, no. 32 (1999): 9817–28. http://dx.doi.org/10.1016/s0040-4020(99)00537-2.

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12

Nicewicz, David A., and Hudson G. Roth. "Diastereoselective Synthesis of the ABCD Ring System of Rubriflordilactone B." Synlett 33, no. 01 (2021): 48–51. http://dx.doi.org/10.1055/a-1659-6521.

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AbstractA novel nine-step diastereoselective route to the ABCD ring system of the natural product rubriflordilactone B is reported. Use of an α-substituted butenolide derived from maleic anhydride facilitated a 1,4-conjugate addition to provide a diene. The order in which a ring-closing metathesis and enolate oxidation were performed on this compound dictated the relative stereochemistry of the target. The final product exhibited anisotropic effects during room-temperature NMR studies, requiring elevated-temperature experiments to confirm its identity.

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13

Besnard, Céline, Christian Kloc, Theo Siegrist, Christer Svensson, and Krystian Pluta. "Diquino[3,4-b;4′,3′-e][1,4]dithiine." Acta Crystallographica Section E Structure Reports Online 62, no. 4 (2006): o1333—o1335. http://dx.doi.org/10.1107/s1600536806007793.

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In the title compound, C18H10N2S2, a crystallographic mirror plane passes through the two S atoms. The pentacyclic ring system is folded along the S—S vector and the central dithiine ring adopts a boat conformation.

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14

Sleziak, Róbert, and Alžbeta Krutošíková. "Cycloaddition Reactions of Furo[2,3-b]pyrroles." Collection of Czechoslovak Chemical Communications 64, no. 2 (1999): 321–28. http://dx.doi.org/10.1135/cccc19990321.

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Reactions of furo[2,3-b]pyrroles with dimethyl butynedioate and ethyl propynoate were investigated. The reaction course is influenced by the substituents on the fused system. Products of [4+2]cycloaddition to the furan ring leading to indole derivatives have been observed. In the case of the reaction of methyl 6H-furo[2,3-b]pyrrole-5-carboxylate (1a) with dimethyl butynedioate, products of [4+2]cycloaddition to the furan ring as well as of Michael addition to the pyrrole ring leading to N-substituted indole derivative 3 have been observed.

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15

FENG, F., and A. MURAI. "ChemInform Abstract: Synthesis of the A- and B-Ring System of Hemibrevetoxin-B." ChemInform 26, no. 27 (2010): no. http://dx.doi.org/10.1002/chin.199527299.

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16

Paterson, Danielle L., and David Barker. "Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B." Beilstein Journal of Organic Chemistry 11 (February 17, 2015): 265–70. http://dx.doi.org/10.3762/bjoc.11.29.

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The synthesis of the unique furo[2,3-b]chromene ring system found in hyperaspidinols A and B, acylphloroglucinols from Hypericum chinense has been achieved in twelve steps. By comparison of the NMR spectra of the synthesized compounds with those of the natural products, a relative stereochemistry is suggested, especially that of the ketal carbon.

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17

Vasanthi, R., D. Reuben Jonathan, K. S. Elizhlarasi, B. K. Revathi, and G. Usha. "Crystal structure of 3-(4-methoxyphenyl)-2,3-dihydro-1H-naphtho[2,1-b]pyran-1-one." Acta Crystallographica Section E Crystallographic Communications 71, no. 5 (2015): o332. http://dx.doi.org/10.1107/s2056989015007082.

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In the title compound, C20H16O3, the hydropyran ring adopts a distorted half-chair conformation with the methine C atom and the ring O atom displaced by −0.554 (2) and 0.158 (1) Å, respectively, from the plane of the other four atoms (r.m.s. deviation = 0.020 Å). Its mean plane (all atoms) is inclined to the naphthalene ring system at a dihedral angle of 11.67 (1)°. The dihedral angle between the napthalene ring system and the phenyl ring is 71.84 (1)°. In the crystal, no diectional interactions beyond van der Waals contacts could be identified.

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18

Swaminathan, K., P. Narayanan, K. Sethusankar, Velu Saravanan, and Arasambattu K. Mohanakrishnan. "Crystal structures of two new carbazole derivatives: 12-(4-nitrophenyl)-7-phenylsulfonyl-7H-benzofuro[2,3-b]carbazole and 2-methyl-4-(4-nitrophenyl)-9-phenylsulfonyl-9H-thieno[2,3-b]carbazole." Acta Crystallographica Section E Crystallographic Communications 72, no. 12 (2016): 1739–43. http://dx.doi.org/10.1107/s2056989016016996.

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The title compounds, C30H18N2O5S, (I), and C27H18N2O4S2, (II), are carbazole derivatives with a phenylsulfonyl group and a nitrophenyl group attached to the carbazole moiety in identical positions in both molecules. A benzofuran ring system in (I) and a methylthiophene ring in (II) are fused with the respective carbazole moieties on the same sides. The mean plane of the carbazole ring system makes a dihedral angle of 3.17 (7)° with the benzofuran ring system in (I) and a dihedral angle of 3.39 (11)° with the methylthiophene ring in (II), implying that both fused units are essentially planar. T

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19

Moskalev, Nikolai V., Gordon W. Gribble, and Jerry P. Jasinski. "4,6-Diphenyl-1-(phenylsulfonyl)-1H-furo[3,4-b]pyrrole." Acta Crystallographica Section E Structure Reports Online 63, no. 3 (2007): o1279—o1281. http://dx.doi.org/10.1107/s1600536807005764.

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The title molecule, C24H17NO3S, is the first example of the 1H-furo[3,4-b]pyrrole ring system to be described. It crystallizes with three molecules in the asymmetric unit. In each molecule, the fused heterocycle is planar and one of the two phenyl groups on the furan ring is only slightly out of planarity with the furan ring, while the other phenyl group is significantly twisted by 47.6 (4), 48.3 (3) and 54.1 (3)°.

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20

Watase, Yasushige. "Embedding Principle for Rings and Abelian Groups." Formalized Mathematics 31, no. 1 (2023): 143–50. http://dx.doi.org/10.2478/forma-2023-0013.

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Summary The article concerns about formalizing a certain lemma on embedding of algebraic structures in the Mizar system, claiming that if a ring A is embedded in a ring B then there exists a ring C which is isomorphic to B and includes A as a subring. This construction applies to algebraic structures such as Abelian groups and rings.

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21

Zhang, Yana, Liandong Guo, and Jing Xu. "Efficient Synthesis of the AC Ring System of Daphnilactone B." Chinese Journal of Organic Chemistry 39, no. 4 (2019): 1079. http://dx.doi.org/10.6023/cjoc201811017.

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22

Rainier, Jon D., Shawn P. Allwein, and Jason M. Cox. "A Highly Efficient Synthesis of the Hemibrevetoxin B Ring System." Organic Letters 2, no. 2 (2000): 231–34. http://dx.doi.org/10.1021/ol991371r.

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23

Enomoto, Masaru, and Shigefumi Kuwahara. "Expeditious Construction of the DEF Ring System of Thiersinine B." Journal of Organic Chemistry 75, no. 18 (2010): 6286–89. http://dx.doi.org/10.1021/jo101258f.

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24

Peng, Yu, Shu-Ming Duan, and Ya-Wen Wang. "Concise synthesis of the DEFG ring system in rubriflordilactone B." Tetrahedron Letters 56, no. 30 (2015): 4509–11. http://dx.doi.org/10.1016/j.tetlet.2015.05.117.

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25

Pyrlik, Jörg. "The HERA-B ring imaging Cherenkov system – design and performance." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 446, no. 1-2 (2000): 299–304. http://dx.doi.org/10.1016/s0168-9002(00)00050-4.

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26

Giacobbe, Simone A., and Romano Di Fabio. "Versatile assembly of the 2-carboxybenzo[b]azepine ring system." Tetrahedron Letters 42, no. 10 (2001): 2027–29. http://dx.doi.org/10.1016/s0040-4039(01)00073-9.

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27

Kido, Fusao, Subhash C. Sinha, Toshiya Abiko, Masataka Watanabe, and Akira Yoshikoshi. "New entry to the perhydrofuro[2,3-b]furan ring system." Journal of the Chemical Society, Chemical Communications, no. 5 (1990): 418. http://dx.doi.org/10.1039/c39900000418.

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28

OLESEN, P. H., J. B. HANSEN, and M. ENGELSTOFT. "ChemInform Abstract: Thieno(2,3-b)indole. The Unsubstituted Ring System." ChemInform 27, no. 13 (2010): no. http://dx.doi.org/10.1002/chin.199613128.

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29

Kaur, Manpreet, Jerry P. Jasinski, Channappa N. Kavitha, Hemmige S. Yathirajan, and K. Byrappa. "[2-(Benzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophen-3-yl](phenyl)methanone." Acta Crystallographica Section E Structure Reports Online 70, no. 5 (2014): o507—o508. http://dx.doi.org/10.1107/s1600536814006679.

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In the title compound, C22H19NOS, the cyclohexene ring of the tetrahydrobenzothiophenyl ring system adopts a slightly distorted half-chair conformation and is twisted slightly [7.5 (8)° for the major disorder component] from the mean plane of the thiophene ring. The dihedral angles between the mean planes of the thiophene ring and the phenyl rings are 65.7 (3) and 8.3 (4)°. The phenyl rings are twisted with respect to each other by 73.8 (7)°. Disorder was modeled for four C atoms of the cyclohexene ring over two sets of sites with an occupancy ratio of 0.659 (2):0.341 (2). In the crystal, a si

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30

El-Hiti, Gamal A., Keith Smith, Amany S. Hegazy, Mansour D. Ajarim, and Benson M. Kariuki. "Crystal structure of 2-(3-nitrophenyl)-1,3-thiazolo[4,5-b]pyridine." Acta Crystallographica Section E Crystallographic Communications 71, no. 11 (2015): o877. http://dx.doi.org/10.1107/s2056989015019118.

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In the title compound, C12H7N3O2S, the dihedral angle between the planes of the thiazolopyridine ring system (r.m.s. deviation = 0.005 Å) and the benzene ring is 3.94 (6)°. The nitro group is rotated by 7.6 (2)° from its attached ring. In the crystal, extensive aromatic π–π stacking [shortest centroid–centroid separation = 3.5295 (9) Å] links the molecules into (001) sheets.

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31

Bakhouch, Mohamed, Abdelali Kerbal, Mohamed El Yazidi, Mohamed Saadi, and Lahcen El Ammari. "Crystal structure of ethyl 2-amino-4-(4-methoxyphenyl)-4H-1-benzothieno[3,2-b]pyran-3-carboxylate." Acta Crystallographica Section E Crystallographic Communications 71, no. 5 (2015): o366—o367. http://dx.doi.org/10.1107/s2056989015008154.

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The molecule of the title compound, C21H19NO4S, features a fused ring system whereby a five-membered ring is flanked by two six-membered rings. This is linked to an ethyl 3-carboxylate group and to a methoxybenzene group. The fused-ring system is quasi-planar, with the greatest deviation from the mean plane being 0.131 (1) Å for the methine C atom. The plane through the methoxybenzene ring is nearly perpendicular to that through the fused-ring system, as indicated by the dihedral angle of 85.72 (6)°. An intramolecular N—H...O hydrogen bond is noted. In the crystal, molecules are linked by N—H.

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32

Afsah, Elsayed M., Ahmed A. Fadda, Samir Bondock, and Mohamed M. Hammouda. "Synthesis and some reactions of functionalized 11,12-dihydro-5H-dibenzo[b,g]azonines." Zeitschrift für Naturforschung B 70, no. 6 (2015): 385–91. http://dx.doi.org/10.1515/znb-2014-0271.

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AbstractDihydro-5H-dibenzo[b,g]azonine-6,13-dione (2) has been used as a precursor in the synthesis of the indolo[2,3-e]dibenzo[b,g]azonine and tribenzo[b,g,j][1,6]diazacyclododecine ring systems 6 and 7 respectively via a Fischer indolization/periodate oxidation sequence. Fischer indolization of the (1,4-phenylenedihydrazono) derivative 8 gave the polycyclic system 9. The Schmidt reaction of 2 led to the formation of the benzimidazo[1,2-b] [2]benzazepine ring system 11. The Mannich reaction of 2 led to the spirocyclic system 15. The reactions of 2 with aldimines and aromatic aldehydes were al

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33

El-Hiti, Gamal A., Keith Smith, Amany S. Hegazy, Mansour D. Ajarim, and Benson M. Kariuki. "Crystal structure of 2-cyclohexyl-1,3-thiazolo[4,5-b]pyridine." Acta Crystallographica Section E Crystallographic Communications 71, no. 11 (2015): o866. http://dx.doi.org/10.1107/s2056989015019106.

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In the title compound, C12H14N2S, the cyclohexane ring adopts a chair conformation with the exocyclic C—C bond in an equatorial orientation. The mean plane through the cyclohexane ring (all atoms) is twisted from the thiazolopyridine ring system (r.m.s. deviation = 0.013 Å) by 39.57 (6)°. In the crystal, molecules form (100) sheets, although there are no specific directional interactions between them. The crystal stucture was refined as a two-component perfect twin.

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34

Barsotti, Jamison, and Rob Carman. "Burnside rings of fusion systems and their unit groups." Journal of Group Theory 23, no. 4 (2020): 709–29. http://dx.doi.org/10.1515/jgth-2019-0145.

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AbstractFor a saturated fusion system {\mathcal{F}} on a p-group S, we study the Burnside ring of the fusion system {B(\mathcal{F})}, as defined by Matthew Gelvin and Sune Reeh, which is a subring of the Burnside ring {B(S)}. We give criteria for an element of {B(S)} to be in {B(\mathcal{F})} determined by the {\mathcal{F}}-automorphism groups of essential subgroups of S. When {\mathcal{F}} is the fusion system induced by a finite group G with S as a Sylow p-group, we show that the restriction of {B(G)} to {B(S)} has image equal to {B(\mathcal{F})}. We also show that, for {p=2}, we can gain in

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35

Marson, Charles M., Jennifer H. Pink, and Christopher Smith. "Synthesis of the first monoaromatic B-ring 13-azasteroid ring system by sequential angular annulation." Tetrahedron 59, no. 50 (2003): 10019–23. http://dx.doi.org/10.1016/j.tet.2003.10.041.

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36

Pappas, Conrad T. E., Peter C. Johnson, and Volker K. H. Sonntag. "Signet-ring cell lymphoma of the central nervous system." Journal of Neurosurgery 69, no. 5 (1988): 789–92. http://dx.doi.org/10.3171/jns.1988.69.5.0789.

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✓ Signet-ring cell lymphoma is a rare tumor described in the lymph nodes, skin, tonsils, thyroid, salivary gland, and ocular orbit. This is the first case report of a B-cell signet-ring cell lymphoma in the central nervous system with Dutcher and Russell bodies, signet-ring nuclei, intracisternal crystalline inclusions, and immunoglobulin M positivity. The patient is doing well 2 years after surgery and postoperative radiation therapy. No definitive prognostic characteristics have been elucidated. This disease entity can only be suspected on histological grounds and confirmed by immunocytochem

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37

Mague, Joel T., Shaaban K. Mohamed, Mehmet Akkurt, Antanr A. Abdelhamid, and Mustafa R. Albayati. "Crystal structure of 2-(11-oxo-10H,11H-indeno[1,2-b]chromen-10-yl)-2,3-dihydro-1H-indene-1,3-dione." Acta Crystallographica Section E Crystallographic Communications 71, no. 5 (2015): o333—o334. http://dx.doi.org/10.1107/s2056989015007495.

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In the title molecule, C25H14O4, the fused-ring system consisting of four rings is approximately planar, with a dihedral angle of 9.62 (5)° between the planes of the indene ring system and the benzene ring. The dihydroindene-1,3-dione unit makes a dihedral angle of 63.50 (2)° with the mean plane of the fused-ring system. A weak C—H...O interaction organizes the molecules into a helical chain along thebaxis. In addition, there is a π–π stacking interaction between the five-membered rings of adjacent fused-ring systems, with a centroid–centroid distance of 3.666 (1) Å.

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38

Griv, Evgeny, Edward Liverts, Michael Gedalin, and Chi Yuan. "Modeling of the Saturnian Ring System." Symposium - International Astronomical Union 208 (2003): 45–52. http://dx.doi.org/10.1017/s0074180900207006.

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A self-consistent system of the Boltzmann equation and the Poisson equation is used to study the dynamical evolution of Saturn's main A, B, and C rings. The theory, as applied to the Saturnian ring system, predicts for several features, such as numerous irregular density wakes, with size and spacing between them of the order 4πρ ≈ 2πh, where ρ is the mean epicycle radius of the particle and h is the typical thickness of the system under study. In Saturn's rings, ρ ≲ 10 m. Computer N-body experiments are desribed which test the validities of the theory. Use of the 112-processor SGI Origin 2000

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39

Rajnikant, Rajnikant, Sarita Parihar, Sabeta Kohli, Sakshi Sharma, B. Narayana, and S. Samshuddin. "Molecular structure elucidation and hydrogen bonding analysis of a pyrazolone derivative." Journal of Applied and Natural Science 3, no. 1 (2011): 86–89. http://dx.doi.org/10.31018/jans.v3i1.160.

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The title compound crystallizes in the monoclinic crystal system with space group P21/c having unit cell parameters: a=7.6329(4), b=7.8137(4), c=28.0651(14) Å, β =95.995o. The structure converges to a final R-value of 0.0563. The two C-N bonds in Ring B are puckered as the torsion around these bonds is 29.67(2)o and -18.49(2)o , respectively. The two methyl carbons as well as the oxygen atom of the central N-containing five-membered ring (B) are significantly deviated from their mean positions. The magnitude of dihedral angle between the phenyl ring A and B is 133.09(1)o while it is 170.43(1)o

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40

Bakhouch, Mohamed, Asmae Mahfoud, Mohamed El Yazidi, Mohamed Saadi, and Lahcen El Ammari. "Crystal structure of ethyl 2-amino-4-(4-chlorophenyl)-4H-1-benzothieno[3,2-b]pyran-3-carboxylate." Acta Crystallographica Section E Crystallographic Communications 71, no. 8 (2015): o619—o620. http://dx.doi.org/10.1107/s2056989015014085.

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The title compound, C20H16ClNO3S, is built up from three fused rings, one five- and two six-membered rings, linked to a 3-ethoxycarbonyl group and to a 4-chlorophenyl ring. The hydropyran ring has a flattened envelope conformation, with the C atom substituted by the 4-chlorophenyl ring as the flap (displaced by 0.077 (2) Å from the plane through the other atoms). The fused three-ring system is quasi-planar (r.m.s. deviation = 0.057 Å), with the largest deviation from the mean plane being 0.106 (1) Å for the C atom substituted by the 4-chlorophenyl ring. The 4-chlorophenyl ring is approximately

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41

Wang, Yong, Yuhan Zhang, Zhongle Li, Zhenjie Yang, and Zhixiang Xie. "A highly efficient synthesis of the DEFG-ring system of rubriflordilactone B." Organic Chemistry Frontiers 4, no. 1 (2017): 47–51. http://dx.doi.org/10.1039/c6qo00241b.

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42

Mohamed, Shaaban K., Joel T. Mague, Mehmet Akkurt, Bahgat R. M. Hussein, and Mustafa R. Albayati. "3,4,6-Triamino-N-phenylthieno[2,3-b]pyridine-2-carboxamide." Acta Crystallographica Section E Structure Reports Online 70, no. 7 (2014): o805. http://dx.doi.org/10.1107/s1600536814013981.

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In the title compound, C14H13N5OS, the dihedral angle between the fused ring system (r.m.s. deviation = 0.028 Å) and the phenyl ring is 48.24 (4)°. The molecule features both an intramolecular N—H...O and an N—H...N hydrogen bond. In the crystal, molecules are linked by N—H...O and N—H...N hydrogen bonds, generating a three-dimensional network. A weak N—H...π interaction is also observed.

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43

Watase, Yasushige. "Zariski Topology." Formalized Mathematics 26, no. 4 (2018): 277–83. http://dx.doi.org/10.2478/forma-2018-0024.

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Summary We formalize in the Mizar system [3], [4] basic definitions of commutative ring theory such as prime spectrum, nilradical, Jacobson radical, local ring, and semi-local ring [5], [6], then formalize proofs of some related theorems along with the first chapter of [1]. The article introduces the so-called Zariski topology. The set of all prime ideals of a commutative ring A is called the prime spectrum of A denoted by Spectrum A. A new functor Spec generates Zariski topology to make Spectrum A a topological space. A different role is given to Spec as a map from a ring morphism of commutat

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44

Irngartinger, Hermann, Jürgen Hauck, Walter Siebert та Manfred Hildenbrand. "Differenzelektronendichte im gefalteten 2 π-aromatischen System eines 1,3-Dihydro-1,3-diborets / Difference Electron Density in a Folded 2π-Aromatic System of a 1,3-Dihydro-1,3-diborete". Zeitschrift für Naturforschung B 46, № 12 (1991): 1621–24. http://dx.doi.org/10.1515/znb-1991-1206.

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The crystal structure and the X—X difference electron density distribution of 1,3-bis(diisopropylamino)-1,3,dihydro-1,3-diborete (1) has been determined at the temperature of 107 K. Both π-electrons of the folded aromatic four membered ring system (folding angle 47.6°) are uniformly distributed on the four ring bonds with equal lengths (B—C 1.524 A). These bonds are significantly bent.

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45

Moss, G. P. "Extension and revision of the von Baeyer system for naming polycyclic compounds (including bicyclic compounds)." Pure and Applied Chemistry 71, no. 3 (1999): 513–29. http://dx.doi.org/10.1351/pac199971030513.

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These recommendations document the von Baeyer system for naming polycyclic ring systems described in Rules A-31, A-32 and B-14 of the Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F and H, 1979 and R-2.4.2 of A Guide to IUPAC Nomenclature of Organic Compounds, 1993 and extend the system to cover more complex cases. It provides guidance on the naming of ring systems which previously the rules did not cover. The methods is to identify the main ring and main bridge which provide the basic bicyclic system and to number these atoms. Then all further bridges, whether or not they include

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Showalter, Mark R. "Dust in Planetary Ring Systems." International Astronomical Union Colloquium 126 (1991): 349–56. http://dx.doi.org/10.1017/s0252921100067105.

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AbstractEach of the outer gas giants Jupiter, Saturn, Uranus and Neptune is now known to be encircled by a system of rings. Some of these, such as the A, B, and C rings of Saturn and the nine narrow Uranian rings, are rather optically thick and are composed primarily of large bodies (1 cm to 10 m). However, every other system has been found to contain a large population of micron-sized dust. Such rings reveal the effects of a variety of physical processes that are also acting on interplanetary and interstellar grains. When such rings are examined as members of a general class, recurring patter

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47

Teixeira, Fátima C., Carla Lucas, M. João M. Curto, Vânia André, M. Teresa Duarte, and António P. S. Teixeira. "Synthesis of novel pyrazolo[3,4-b]quinolinebisphosphonic acids and an unexpected intramolecular cyclization and phosphonylation reaction." Organic & Biomolecular Chemistry 19, no. 11 (2021): 2533–45. http://dx.doi.org/10.1039/d1ob00025j.

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Novel pyrazolo[3,4-b]quinolinebisphosphonic acid derivatives were synthesized. An unexpected cascade reaction was observed, with the phosphonylation of an aromatic ring and the formation of a new tetracyclic ring system.

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Liang, Xiao-Xia, Pei Tang, Qiao-Hong Chen, and Feng-Peng Wang. "Synthesis of Taxane ABC Tricyclic Skeleton from Lycoctonine." Natural Product Communications 7, no. 6 (2012): 1934578X1200700. http://dx.doi.org/10.1177/1934578x1200700603.

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A new conversional synthesis of the ABC ring system of taxoids from the C19-diterpenoid alkaloid lycoctonine was developed in 6 steps with 2% overall yield. The distinctive features of the conversion include pinacol rearrangement, enlargement of ring B, and opening of a four-membered ring.

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Badenock, Jeanese C., Heidi L. Fraser, and Gordon W. Gribble. "A new approach to the pyrrolo[3,4-b]indole ring system." Arkivoc 2018, no. 5 (2018): 140–49. http://dx.doi.org/10.24820/ark.5550190.p010.584.

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Cirrincione, Girolamo, Patrizia Diana, Alessandra Passannanti, Paola Barraja, and Antonino Lauria. "Pyrrolo[2,3-b][1,4]benzothiazine. A New Ring System from Azidopyrroles." HETEROCYCLES 51, no. 9 (1999): 2103. http://dx.doi.org/10.3987/com-99-8604.

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