Lithiation of 1,2,3-triazolo[1,5-a]pyridines 4b and 4c with Lithium di
isopropylamide (LDA) gave the corresponding lithio derivatives 5b and
5c from which esters 6b and 6c were obtained by treatment with carbon
dioxide and then dimethyl sulfate. Lithio derivatives 5a-5c reacted wi
th DMF giving aldehydes 7a-7c. Esters 9a-9c were prepared from aldehyd
es 7a-7c and carbomethoxymethylenetriphenylphosphorane.