Enantioselective syntheses of (+)- and (−)-Phaseolinic acid
作者:Peter A. Jacobi、Prudencio Herradura
DOI:10.1016/0040-4039(96)01941-7
日期:1996.11
(+)- and (−)-Phaseolinicacid (1) have been prepared in an enantioselective fashion from acetylenic acid 26 (or ent-26) by a three step sequence involving lactonization, epimerization at C3, and oxidative cleavage. 26 was obtained as a single enantiomer using a Nicholas-Schreiber reaction.
An unequivocal synthesis of the ring-A,B dihydropyrromethenone of phytochrome
作者:Peter A. Jacobi、Jiasheng Guo、Wanjun Zheng
DOI:10.1016/0040-4039(95)00032-8
日期:1995.2
Dihydropyrromethenone 1b (R = p-methoxybenzyl), a potential precursor for the synthesis of phytochrome (3), has been prepared in enantiomerically pure form beginning with the homochiral acetylenic lactone 18.
Formal Total Syntheses of the β-Lactam Antibiotics Thienamycin and PS-5
作者:Peter A. Jacobi、Shaun Murphree、Frederic Rupprecht、Wanjun Zheng
DOI:10.1021/jo952092u
日期:1996.1.1
Chiral nonracemic acetylenic acids of general structure 11, prepared using the Schreiber modification of the Nicholas reaction, have been converted to beta-amino acid derivatives of type 12 by a two-step sequence involving Curtius rearrangement followed by oxidative cleavage of the acetylenic bond. Amino acid derivatives 12 are excellent precursors for beta-lactams of the carbapenem class, including the important antibiotics thienamycin (1) and PS-5 (4).
Dihydropyrromethenones by Pd(0)-Mediated Coupling of Iodopyrroles and Acetylenic Amides. Synthesis of the A,B-Ring Segment of Phytochrome
作者:Peter A. Jacobi、Jiasheng Guo、S. Rajeswari、Wanjun Zheng
DOI:10.1021/jo970289b
日期:1997.5.1
Dihydropyrromethenone derivative 32b, which constitutes the A,B-ring segment of phytochrome (6), has been prepared in enantiomerically pure form beginning with acetylenic amide 47b and iodopyrrole 27. The key steps involved the TBAF-catalyzed 5-exo-dig cyclization of the acetylenic pyrrole 48b, followed by thia-Mitsunobu inversion of the resulting alcohol derivative 31b.