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
摘要:
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.
Synthesis of Type II β-Turn Surrogate Dipeptides Based on <i>s</i><i>yn</i>-α-Amino-α,β-dialkyl-β-lactams
作者:Claudio Palomo、Jesus M. Aizpurua、Iñaki Ganboa、Ana Benito、Lourdes Cuerdo、Raluca M. Fratila、Azucena Jimenez、Iraida Loinaz、José I. Miranda、Kinga R. Pytlewska、Andreea Micle、Anthony Linden
DOI:10.1021/ol048348c
日期:2004.11.1
The achiral bis(trimethylsilyl)methyl group acts as an efficient stereochemical determinant of the alpha-alkylation reaction in beta-branched alpha-phenyloxazolidinyl- or alpha-diphenyloxazolidinyl-beta-lactams and provides the first stereocontrolled access to syn-alpha-amino-alpha,beta-dialkyl(aryl)-beta-lactams. These products are readily transformed into type II beta-turn mimetic surrogates 2B.