Parallel solution phase synthesis of benzyl (3S,4E)-4-[(arylamino)methylidene]-5-oxotetrahydrofuran-3-ylcarbamates

Abstract

Benzyl (3S,4E)-4-[(dimethylamino)methylidene]-5-oxotetrahydrofuran-3-ylcarbamate 5 was prepared in 4 steps from L-aspartic acid 1. Acid-catalysed treatment of 5 with amines 6 gave the dimethylamine substitution products 7. Benzyl (3S,4E)-4-[(arylamino)methylidene]-5oxotetrahydrofuran-3-ylcarbamates 7c-n were prepared by parallel solution phase synthesis from 5 and anilines 6c-n in 45-94% yields. Enaminone 5 reacted with potassium cyanide in the presence of 18-crown-6 to afford benzyl 4-cyanomethyl-5-oxo-2,5-dihydrofuran-3-ylcarbamate 9. Upon reaction of 9 with nitrile oxide 10 the 1,2,4-oxadiazole derivative 11 was isolated in poor yield, while treatment of 9 with diazomethane 12 furnished the methylation products 13 and 14.