PHASE-TRANSFER-CATALYZED (PTC) REACTIONS OF CHLOROFORM WITH ALKENYL CARBOXYLATES - EFFECT OF CATALYST STRUCTURE ON REACTION COURSE

Reaction of chloroform with ketone enol esters 1d,e carried out in the presence of 50% aq NaOH and benzyltriethylammonium chloride (TEBAC) a s a catalyst gives gem-dichlorocyclopropanes 3d,e In the case of enol esters of aldehydes, adducts of trichloromethyl anion 2a,b,f,h (from 1 a,b,f,h) or mixtures of 2 and 3 (from 1c,g,i) are formed. The same rea ction carried out with a catalytic amount of tetramethylammonium hydro gen sulphate (TMAHS) yields mixtures of 2 and 3, highly enriched in th e latter products, or pure 3i from 1i. The kind of the products formed depends on ease of cleavage of 1 by base, nucleophilicity of carbon-c arbon double bond in 1, and type of the catalyst applied. Copyright (C ) 1996 Elsevier Science Ltd