1, 3-Oxazines and Related Compounds. XIV. Facile Synthesis of 2, 3, 6-Trisubstituted 2, 3-Dihydro-1, 3-oxazine-5-carboxylic Acids and 1, 4-Disubstituted 3-Acyl-β-lactams from Acyl Meldrum's Acids and Schiff Bases

Abstract

Simple preparations of 2, 3, 6-trisubstituted 2, 3-dihydro-1, 3-oxazine-5-carboxylic acids (4) and 1, 4-disubstituted 3-acyl-β-lactams (5) from acyl Meldrum's acids and Schiff bases were carried out. 2, 3-Disubstituted 5-acy1-3, 4, 5, 6-tetrahydro-2H-1, 3-oxazine-4, 6-diones (3) were isomerized to 4 in a chlorotrimethylsilane?triethylamine system and to 5 by hydrogen chloride.