Benzothiazines in Synthesis. A Formal Total Synthesis of Pseudopteroxazole

A formal total synthesis of the antitubercular natural product was accomplished. This work was undertaken to address certain stereochemical problems in our initial synthesis. By using an ester group as a surrogate for a methyl group, we were able to intercept a key intermediate in our first synthesis with better selectivity and greater convergence than had previously been the case.