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.