A-Hydrazinocarboxylic acid

The reaction has been extensively used for the synthesis of a-amino acids (entries 3-5),559 //-/ -amino alcohols (entry 6),560 aminophenol (entry 7),561 optically active A-substituted glycines (entries 7 and 8),562 a-hydrazinocarboxylic acids (entry 9),563 A-sulfinyl and A-alkoxy-a-amino acids (entries 10 and ll),564 and propargyl amines (entry 12).565... 

Sodium ethoxide 4-Hydroxypyiidaziiiiiim betaines from a-hydrazinocarboxylic acid esters via Dieckmann cyclization... 

Aminohydantoins from a-chlorocarboxylic acids via a-hydrazinocarboxylic acids 1-Alkylideneaminohydantoins from aldehyde acetates... 

Sodium carbonate a-Hydrazinocarboxylic acid esters from 1,2-diazetidinones... 

With a-hydrazinocarboxylates (613) instead of hydrazonocarboxylic acids, imidates give the dihydro-1,2,4-triazin-5-ones (614) (1895CB1223,64LA(676)l2l). 

The cyclic ot-hydrazinocarboxylic acids (/ )- and (5)-piperazic acid (140) are present in a variety of bioactive cyclodepsipeptides. Harmda et al. have developed a highly efficient synthesis of (/ )-(140) by reacting 5-bromovaleraldehyde (141) with azodicarboxyl ate 142 in the presence of 10 mol% (5)-12 (128). The reaction product was directly treated with NaBELj to give the alcohol 143 in excellent yield and enantioselectivity. The product 140 could then be obtained successfully after cyclization, oxidation, and Cbz-cleavage (Scheme 34). 

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