A facile stereospecific synthesis of α-hydrazino esters

N-Substituted 3-Acetyltetramic Acid Derivatives as Antibacterial Agents

“…N-Substituted secondary amines 8a-g were synthesized by reductive amination reactions of the amino acid ester salts with various alkyl and aryl aldehydes in THF in the presence of MgSO 4 and Et 3 N for 5 h, and the resulting imines were reduced using NaBH 4 in methanol for 30 min. 17 Subsequently, secondary amines 8a-g were converted into their respective cyanoamides by reacting them with the cyanoacetic acid in DCM in the presence of DIC or DCC and HOBt at rt for 6 h to afford cyanoamide intermediates. The cyanoamides were then cyclized into tetramic acids by using Amberlyst A-26 hydroxide resin in methanol at rt for 2 h. 16 The use of a solid-phase resin during the cyclization step eliminates the need for column purification by acting both as a reaction catalyst and as scavenger resin for the product.…”

“…To investigate the importance of acyl substituents at the 3-position on the tetramic acid core, N-substituted 3-cyanotetramic acid derivatives 9a − g (Scheme ) were synthesized using the method described by Kulkarni et al l -Amino acid ester salts were used as starting materials for the synthesis of compounds 9a − e and d -amino acid ester salts were used as starting materials for the synthesis of compounds 9f , g . N-Substituted secondary amines 8a − g were synthesized by reductive amination reactions of the amino acid ester salts with various alkyl and aryl aldehydes in THF in the presence of MgSO 4 and Et 3 N for 5 h, and the resulting imines were reduced using NaBH 4 in methanol for 30 min . Subsequently, secondary amines 8a − g were converted into their respective cyanoamides by reacting them with the cyanoacetic acid in DCM in the presence of DIC or DCC and HOBt at rt for 6 h to afford cyanoamide intermediates.…”

Peptidomimetics via modifications of amino acids and peptide bonds

“…[244][245][246] Recently, N-Boc-Otosylhydroxylamine has proved to be a NH-Boc transfer reagent by converting chiral amino acids to Boc-protected hydrazino acids. 247 Reduction of N a -nitrosoamino acids 213,248,249 and rearrangement of the hydantoic acids 250,251 are alternative access routes to hydrazinoacids from amino acids.…”

Synthesis and Chemistry of α‐Hydrazino Acids

“…N-Nitroso proline [25] or N-benzyl,N-nitroso-aamino esters 40 were quantitatively obtained using these reagents [98,155,156] (Scheme 2.16). N-Nitroso proline [25] or N-benzyl,N-nitroso-aamino esters 40 were quantitatively obtained using these reagents [98,155,156] (Scheme 2.16).…”

“…Hydrogenolysis of a-hydrazino acid derivatives that are N 1 ,N 2 -unsubstituted or substituted by aryl or alkyl substituents also occurs using palladium hydroxide [181] or platinum [190] [190] 64j 2 Synthesis and Chemistry of a-Hydrazino Acids LiOAc/AcOH mixture at pH 7-8 [195] 66j 2 Synthesis and Chemistry of a-Hydrazino Acids oxide [108,110,188,193]. Hydrogen and palladium on charcoal are selective for benzyl or benzyloxycarbonyl groups and are generally unable to cleave NÀN bonds [59,68,109,111,156,173], except in the case of aminoserine, which has been converted to serine [165]. Hydrogen and palladium on charcoal are selective for benzyl or benzyloxycarbonyl groups and are generally unable to cleave NÀN bonds [59,68,109,111,156,173], except in the case of aminoserine, which has been converted to serine [165].…”