1, 3-Dipolar Cycloaddition Reaction of 2-[(Trimethylsilylmethylamino)(methylthio)]methylene-1, 3-indandione and 2-[(Trimethylsilylmethylthio)(methylthio)]methylene-1, 3-indandione : Synthetic Equivalents of Cyclic Dicarbonyl Alkylideneazomethine and Alkylidenethiocarbonyl Ylides as Novel 1, 3-Dipolar Reagents

Abstract

2-[(Trimethylsilylmethylamino)(methylthio)]methylene- and 2-[(trimethylsilylmethylthio)(methylthio)]methylene-1, 3-indandiones (1a, b), which are readily prepared by reaction of the corresponding 2-bis(methylthio)methylene-1, 3-indandione (12) with trimethylsilylmethylamine (13a) and trimethylsilylmethylmercaptan (13b), were found to be synthetic equivalents of carbonyl alkylidene-azomethine and alkylidene-thiocarbonyl ylides. Reaction of 1a, b with reactive hetero-dipolarophiles such as aldehydes and ketones and reactive alkenes in the presence of cesium fluoride gave 1, 3-dipolar cycloadducts, 4, 5-dihydro-2-(1, 3-dioxoindan-2-ylidene)-1, 3-oxazoles (6a-f, 7a-c), 4, 5-dihydro-2-(1, 3-dioxoindan-2-ylidene)pyrroles (8a-c), 2-alkylidene-1, 3-oxathiolanes (9a-k, 10a, b), and 2-alkylidenethiophenes (11a-c), via formation of the counterpart of the carbonyl-substituted intermediate with concomitant desilylation.