Process for preparing a dipeptidyl peptidase IV inhibitor and intermediates employed therein

A process is provided for preparing a dipeptidyl peptidase IV inhibitor of the structure wherein is treated with TFAA in isopropyl acetate to protect the tertiary hydroxyl group as a trifluoroacetate group to form 4 (which is a novel intermediate) which is converted to acid chloride compound 5 (which is a novel compound) using Vilsmeier reagent or other chloro reagent and coupled with compound 6 in a heterogeneous mixture of ethyl acetate and aqueous bicarbonate to give compound 7 The N,O-bis(trifluoroacetyl) groups of compound 7 are deprotected to give free base compound 10.