Michael reaction of [alpha]-chloro sulfonyl carbanion

Abstract

The purpose of this research is to study the reaction of α-chloaro sulfonyl carbanion with various α,β-unsaturated compounds of monoesters, diesters, mononitrile, dinitrile, aldehydes, ketones, 1,3-ketorster, and 1,3-diketone. The two method for generating the α-chloro sulfonyl carbanion were investigates i.e. : 1. Lithium diisopropylamide (LDA) in tetrahydrofuran (THF) with hexamethylphosphoramide (HMPA) as a cobolvent (LDA method) 2. K(,2)Co(,3)/ benzyltriethylammonium chloride (TEBA) / aprotic solvent (PTC method) The results from the investigations could be summarized as follows : 1. Reaction of lithio chlormethyl phenyl sulfone anion with alpha, beta-unsaturated monoesters, diesters, mono and dinitrile gave the corresponding cyclopanes. 2. Reaction of alpha-chloro sulfonyl carbaion with methyl acrylate and crotonitrile yielded the cyclopentyl products in low yields. These products derived from a 1+2+2 MIMI-RC reaction. The reaction of methyl acrylate with alpha-chloro sulfonyl carbanion gave cyclohexyl derivative. This product could derived from a Michael-Michael-Dieckmann reaction. 3. The products from the reaction of α-chloro sulfonyl carbanion with α,β-unsaturated ketones depended no the tpye of ketones. The results obtained as follows.a. Methyl vinyl ketone, the major products are the corresponding cyclopropane and cyclohexyl compounds derived from Michael-Michael-Aldol reaction.b. Chalcone gave cyclopropanes and cyclopropyl epoxide.c. Dibenzalacetone, only cyclopropyl products were isolated.d. Cyclopentenone and cyclohexennone yielded cyclopropyl derivatives and the tricyclic compounds. These reactions provide a quick entry to polycyclic compounds. 4. The addition of lithio chloromethyl phenyl sulfone anion to α,β-unsaturated aldehydes gave 1,2-addition product exclusively. 5. The reaction of α,β-unsaturated 1,3-ketoester with lithio chloromethyl phenyl sulfone anion gave the expected cyclopropane in good yield. For α,β-unsaturated 1,3-diketone, dihydrofuran derivative was isolated in high yield.