Academic literature on the topic 'Rosero Diago'

Nigel S. Simpkins, now at the University of Birmingham, found (Chem. Commun. 2008, 5390) that the prochiral cyclopropane amide 1 could be deprotonated to give, after alkylation, the substituted cyclopropane 3 with high enanantio- and diastereocontrol. In the course of a synthesis of (+)-Lineatin, Ramon Alibés of the Universitat Autònoma de Barcelona optimized (J. Org. Chem. 2008, 73, 5944) the photochemical cycloaddition of 4 and 5 to give, after reductive dechlorination, the cyclobutene 6. In a related reaction, José L. García Ruano and M. Rosario Martín of the Universidad Autónoma de Madrid observed (J. Org. Chem. 2008, 73, 9366) that the cycloaddition of 8 to 7 proceeded with high regio- and diastereocontrol, to give the cyclopentene 9. Joseph M. Ready of UT Southwestern in Dallas developed (Angew. Chem. Int. Ed. 2008, 47, 7068) a powerful new cyclopentannulation, condensing the cyclopropane derived from the addition of 11 to 10 with the protected ynolate 12 to give 13, in the presence of a modified Lewis acid catalyst. Chun-Chen Liao of the National Tsing Hua University, Hsinchu described (Angew. Chem. Int. Ed. 2008, 47, 7325) the oxidative ring contraction of the o-alkoxy phenol 14 to the cyclopentenone 15. Stéphane Quideau of the Université de Bordeaux reported (Organic Lett. 2008, 10, 5211) a related ring contraction. We uncovered (J. Org. Chem. 2008, 73, 9479) a simple protocol for the in situ conversion of an ω-alkenyl ketone such as 16 to the corresponding diazo compound, leading, via dipolar cycloaddition, to the adduct 17. Ulrich Zutter of Roche Basel described (J. Org. Chem. 2008 , 73, 4895), in a synthesis of Tamiflu, the hydrogenation of 19 to give the cyclohexane with all-cis diastereocontrol. Selective removal of the methyl ethers with trimethylsilyl iodide set the stage for enzymatic ester hydrolysis, delivering 20 in high ee.

One of the most powerful of alkene transformations is enantioselective epoxidation. Tsutomu Katsuki of Kyushu University has developed (Angew. Chem. Int. Ed. 2007, 46, 4559) a Ti catalyst that with H2O2, selectively epoxidized terminal alkenes with high ee. The same catalyst converted a Z 2-alkene such as 3 into the epoxide. This is significant, because such epoxides are opened with nucleophiles selectively at the less congested center. Novel procedures for alkene functionalization have been put forward. Philippe Renaud of the University of Berne has developed (Adv. Synth. Cat. 2008, 350, 1163) a simple protocol for terminal halogenation, based on catalyzed addition of catecholborane, followed by free radical substitution. Sulfides and selenides were also prepared. H. Zoghlami of the Faculty of Sciences of Tunis has devised (Tetrahedron Lett. 2007, 48, 5645) an oxidative sulfinylation, converting a terminal alkene 7 to the sulfide 8. M. Christina White of the University of Illinois (J. Am. Chem. Soc. 2008, 130, 3316) and Guosheng Liu of the Shanghai Institute of Organic Chemistry (Angew. Chem. Int. Ed. 2008, 47, 4733) independently developed Pd catalysts for the oxidation of a terminal alkene 9 to the terminal allylic amine 10. Shannon S. Stahl of the University of Wisconsin-Madison has established (Organic Lett. 2007, 9, 4331) conditions for the complementary transformation of a terminal alkene 11 to the enamide 12. Douglas B. Grotjahn of San Diego State University has optimized (J. Am. Chem. Soc. 2007, 129, 9592) Ru-catalyzed alkene (“zipper”) migration, effecting the conversion of 13 to 14 and of 15 to 16 . There have been several new observations on alkene cleavage. Marcus A. Tius of the University of Hawaii and Bakthan Singaram of the University of California, Santa Cruz have found (Tetrahedron Lett. 2008, 49, 2764) that epoxides such as 17 are cleaved directly by NaIO4, providing a simple alternative to ozonolysis. Rolando A. Spanevello of the Universidad Nacional de Rosario has extended (Tetrahedron 2007, 63, 11410) unsymmetrical ozonolysis to highly substituted norbornene derivatives such as 19, observing 20 as the only product. Patrick H. Dussault of the University of Nebraska–Lincoln has established (J. Org. Chem. 2008, 73, 4688) that alkene ozonolysis in wet acetone delivered the ketone or aldehyde directly, without reductive workup.