Additions and Corrections - Reaction of N-Disubstituted Glycyl Chlorides with Diazomethane

Abstract

It is possible to conduct all operations under such mild conditions, in particular by working at sufficiently low temperatures, that the configuration of the H 2 N -C ( R ) Hgroup remains unchanged [ 1 151, just as in the similar synthesis of the aminopyruvaldehyde derivatives (101) + (105) + (106) [I151 (see also Section II.3a); no racemization or Walden inversion occurs. a-Hydroxy-oaminocarboxylic acids (107) are also accessible in this way from (104), (105), or (106). By condensing the a-keto-6-aminovaleric acid obtained in this manner with o-aminobenzaldehyde, Machokin [ 1 161 was able to synthetize deoxyvasicine, in analogy to the synthesis developed by Schiipf [I 171 starting from y-aminobutyraldehyde and o-aminobenzaldehyde. In the first communication of this series [118], additional preparative applications proceeding by way of a-

A Three-Step General Synthesis of 2-Azetidinones Bearing N-Dehydroamino Acid Side Chains

“…Optical compounds to the synthesis of bi-and tricyclic β-lactam rotations were measured with a Perkin-Elmer 241 apparatus at products are presented in Scheme 4. The following chemicals were prepared according to istry remained unaltered during the formation of tricycle literature procedures: phthalimidoacetyl chloride, [31] 2,3-O-(isopro-10, as confirmed by 1 H-NMR analysis in the presence of pylidene)--glyceraldehyde, [32] and (S)-(4-phenyl-2-oxooxazolidinyl)acetyl chloride. Specific rotation values pared from compound (3R,4S)-7f by standard ketal depro-[α] D are given in deg per dm, and the concentration (c) is expressed tection with TsOH followed by purification by flash column in g per 100 ml in CHCl 3 .…”

3.19 The Wolff Rearrangement

“…Initial experiments in the field demonstrated that disubstituted amino glycyl chloride, N-phthaloylglycyl chloride can be acylated in diazomethane furnishing the desired diazoketone. 216 Meanwhile, the utilization of Boc-and Z-protected amino acids chlorides led to partial racemization and decomposition toward Leuchs anhydrides 236. 216,217 The formation of HCl during the preparation of acyl chloride can potentiate the loss of the amino protecting groups, providing the Leuchs anhydrides 236 on reaction with the activating reagents (Scheme 68).…”

“…216 Meanwhile, the utilization of Boc-and Z-protected amino acids chlorides led to partial racemization and decomposition toward Leuchs anhydrides 236. 216,217 The formation of HCl during the preparation of acyl chloride can potentiate the loss of the amino protecting groups, providing the Leuchs anhydrides 236 on reaction with the activating reagents (Scheme 68). In addition, the basic conditions used to scavenge HCl promote racemization.…”