Treatment of methyl p-aminobenzoate with dimethyl sulfide, followed immediately by the addition of N-chlorosuccinimide in CH2C12 at-25" C, gave a white slurry, which, upon extraction with 5% sodium hydroxide, gave a solution of the sulfilimine 2 (Scheme I). Oxidation of 2 in situ at 0" C to methyl p-nitrosobenzoate (3) was accomplished by addition of 1.2 equiv of m-chloroperbenzoic acid. Diels-Alder reaction of 3 with 2-methoxy-1, 3- ...