Direct conversion of esters to secondary amides using Tin(II) reagents

Article abstract of DOI:10.1016/S0040-4039(00)79291-4

We have developed tow new procedures for the direct conversion of esters to secondary amides. In our first procedure, secondary amides can be prepared in 83-98% yield starting from glycol esters. Addition of Sn[N(TMS)₂]₂ and a primary amine to the glycol ester generates an intermediate tin(II) akoxy amide, which delivers the amino group intramolecularly to give the amide. A second general procedure for the preparation of secondary amides starts with methyl esters. Treatment of methyl esters with a tin reagent derived from Sn[N(TMS)₂]₂, Me₂NCH₂CH₂OH, and a primary amine yields secondary amides in 87-98% yield.