Construction of Quaternary Stereogenic Centers via [2 + 2] Cycloaddition Reactions. Synthesis of Homochiral 4,4-Disubstituted 2-Azetidinones and Imine Substituent Effects on β-Lactam Formation
作者:Claudio Palomo、Jesus M. Aizpurua、Jesus M. García、Regina Galarza、Marta Legido、Raquel Urchegui、Pascual Román、Antonio Luque、Juan Server-Carrió、Anthony Linden
DOI:10.1021/jo962017z
日期:1997.4.1
A study on the asymmetric construction of quaternary stereogenic centers via [2 + 2] cycloadditionreaction of ketenes with ketimines is described. Reaction of achiral ketenes and chiral alpha-alkoxy ketone-derived imines resulted in formation of new beta-lactams as single diastereomers. The cycloaddition was extended to pyruvate imines, aralkyl ketone-derived imines, and dialkyl ketimines. In these
Reaction of [bis(trimethylsilyl)methyl]amine with aldehydes, leads to Schiff bases with unexpected remarkable stability.
A Contribution to the Asymmetric Synthesis of 3-Amino β-Lactams: The Diastereoselective [2+2] Cycloaddition Reaction of Chiral Aminoketene Equivalents with Enolizable Aldehyde-Derived Imines
作者:Claudio Palomo、Jesus M. Aizpurua、Marta Legido、Antonia Mielgo、Regina Galarza
DOI:10.1002/chem.19970030909
日期:1997.9
AbstractN‐[Bis(trimethylsilyl)methyl]imines 9 show unique chemical properties when compared with conventional imines. Their reaction with optically pure aminoketenes derived from dehydrochlorination of 14 and 15 affords the corresponding 3‐amino‐4‐alkyl‐β‐lactams 16 and 17 in good yields and high diastereoselectivities. The mild deprotection of bis(trimethylsilyl)methyl‐ and phenyloxazolidinone moieties with, respectively, cerium(IV) ammonium nitrate and lithium/ammonia or hydrogen/Pd(OH)2 allows the preparation of a variety of β‐lactam antibiotic building blocks.
Palomo, Claudio; Aizpurua, Jesus M.; Legido, Marta, Angewandte Chemie, 1996, vol. 108, # 11, p. 1317 - 1318
作者:Palomo, Claudio、Aizpurua, Jesus M.、Legido, Marta、Galarza, Regina、Deya, Pere M.、et al.