Approaches to installing a N-gem-dimethylmethylene-2-oxazolyl group and application to the synthesis of a second generation HIV protease inhibitor

Two syntheses of the title compound 1 are described based on different approaches for installing the oxazole ring moiety. Formation and dehydration of ketoamide (A) was initially used and scaled up on several kilogram scale, then oxazole anion/iminium coupling (B) was developed for a more convergent approach.