Formal [3+2] Cycloaddition Reactions of 1-Methyl-2-[methylthio-(trimethylsilylmethylimino)methylimino]-1, 2-dihydropyridine and Related Compound with Carbonyl Compounds Promoted by Fluoride Ion

Abstract

Reaction of 1-methyl-2-[methylthio(trimethylsilylmethylimino)methylimino]-1, 2-dihydropyridine (1), prepared from 2-amino-1-methyl-pyridinium iodide in 3 steps, with carbonyl compounds in the presence of 2 eq of cesium fluoride in acetonitrile afforded 2-(1-methyl-1, 2-dihydropyridylidene)aminooxazoline derivatives (12), which correspond to formal [3+2] cycloadducts of the aminonitrile ylid. Further, compound 1 reacted with carbonyl compounds in the presence of a catalytic amount of tetra-n-butylammonium fluoride (TBAF) to give corresponding cycloadducts.