Synthetic Reactions of Isoxazoline 2-oxides. Part XIV. New Route to 1,3,3a,8a-Tetrahydro-2H-benzofuro(2,3-b)pyrrol-2-ones from Methyl .ALPHA.-Hydroxy-4H-1,2-benzoxazine-4-acetates Obtained by Ring Transformation of 4-Aryl-2-isoxazoline 2-Oxides.

Abstract

4-Aryl-2-isoxazoline 2-oxides (1) were converted to methyl α-hydroxy-3-methoxycarbonyl-4H-1, 2-benzoxazine-4-acetates (3) upon treatment with a Lewis acid such as titanium tetrachloride. The structure of 3 was confirmed by X-ray analysis. Tosylates of 3 were treated with triethylamine to yield (E)- and (Z)- isomers of olefins (5) with (E)-preference. Catalytic reduction of each isomer of 5 produced 5, 8a-disubstituted 1, 3, 3a, 8a-tetrahydro-2H-benzofuro[2, 3-b]pyrrol-2-ones (6) in moderate yields.