One-carbon homologation of aryl and alkyl aldehydes to amides using BtCH2P+Ph3C-

Alan R Katritzky,Geoffroy L Sommen,Rong Jiang,Sandeep K Singh,Viktor V Zhdankin

doi:10.3998/ark.5550190.0005.907

Abstract

One-carbon homologated amides have been prepared from aryl and alkyl aldehydes. Vinyl benzotriazoles 6, prepared by the reaction of aldehydes with the one-carbon synthon BtCH2P + Ph3Cl - (5), were subsequently brominated to give 1,2-dibromo-benzotriazolylalkanes 7. Treatment of 7 with a variety of aryl or alkyl amines in the presence of water furnished one- carbon homologated amides 8ain 32 yields. This method works well with both primary and secondary aryl or alkyl amines.

Highlights

Previous methods for the one-carbon homologation of aldehydes to amides have mostly involved the one-carbon homologation of aldehydes 1 to carboxylic acids 3 followed by a functional group transformation to amides 4 (Scheme 1)
Syntheses of intermediates 2a-j and subsequent conversion to carboxylic acids 3 often require harsh conditions that are incompatible with sensitive functional groups
Carbon homologation of aldehydes to amides using 1,1-dibromo-1-alkenes 2m offers a short route, good yields and mild reaction conditions that tolerate a range of functionalities but it is inapplicable to alkyl aldehydes and aryl amines and uses carcinogenic carbon tetrabromide (Scheme 1).[3,4]

Summary

Introduction

Previous methods for the one-carbon homologation of aldehydes to amides have mostly involved the one-carbon homologation of aldehydes 1 to carboxylic acids 3 followed by a functional group transformation to amides 4 (Scheme 1). A one-pot procedure via 1-(benzotriazol-1-yl)-1-methoxyalk-1-enes 2k for the preparation of homologated carboxylic acids from aldehydes has been reported (Scheme 1).[2] Amine solvolysis of α-alkoxyacrylonitriles 2l gives one-carbon homologated amides directly but is inapplicable to substrates with acid-labile groups (Scheme 1).1a The recently reported one- Carbon homologation of aldehydes to amides using 1,1-dibromo-1-alkenes 2m offers a short route, good yields and mild reaction conditions that tolerate a range of functionalities but it is inapplicable to alkyl aldehydes and aryl amines and uses carcinogenic carbon tetrabromide (Scheme 1).[3,4]

Results

Conclusion