A CONTRIBUTION TO THE ASYMMETRIC-SYNTHESIS OF 3-AMINO BETA-LACTAMS - THE DIASTEREOSELECTIVE [2-DERIVED IMINES(2]CYCLOADDITION REACTION OF CHIRAL AMINOKETENE EQUIVALENTS WITH ENOLIZABLE ALDEHYDE)
C. Palomo et al., A CONTRIBUTION TO THE ASYMMETRIC-SYNTHESIS OF 3-AMINO BETA-LACTAMS - THE DIASTEREOSELECTIVE [2-DERIVED IMINES(2]CYCLOADDITION REACTION OF CHIRAL AMINOKETENE EQUIVALENTS WITH ENOLIZABLE ALDEHYDE), Chemistry, 3(9), 1997, pp. 1432-1441
N-[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 afford
s the corresponding 3-amino-4-alkyl-beta-lactams 16 and 17 in good yie
lds and high diastereoselectivities. The mild deprotection of bis(trim
ethylsilyl)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 beta-lactam antibiotic buildi
ng blocks.