Metal-assisted fragmentation of N-aryl- and -alkyl-N-trimethyl-silylaminosulfur chlorides and N-aryl- and -alkyl-aminosulfur chlorides in the presence of conjugated dienes: synthesis and reactivity of 2-substituted-3,6-dihydro-1,2-thiazines

Abstract

N-Alkyl- and -aryl-N-trimethylsilylaminosulfur chlorides 2 and N-aryl- and -alkyl-aminosulfur chlorides 8 fragment in the presence of silver ions and a conjugated diene to yield 2-substituted-3,6-dihydro-1,2-thiazines 6 as the major products, possibly via transient metal-coordinated thionitroso species. By judicious choice of the substituent on the nitrogen atom, the 1,2-thiazines 6 can be stabilised by an intramolecular non-bonded oxygen ⋯ sulfur or sulfur ⋯ sulfur interaction, e.g. structures 9 and 6j. Reactions of 1,2-thiazine derivatives 6g and 6i with butyllithium, followed by addition of methyl iodide, afforded the ring-opened products 21g and 21i, respectively. Reaction of transient pentacarbonyl-(tetrahydrofuran)chromium with compound 6b afforded the pentacarbonylchromium derivative 22 which was characterised by X-ray crystallography.