M. Fedorynski et al., PHASE-TRANSFER-CATALYZED (PTC) REACTIONS OF CHLOROFORM WITH ALKENYL CARBOXYLATES - EFFECT OF CATALYST STRUCTURE ON REACTION COURSE, Tetrahedron, 53(3), 1997, pp. 1053-1060
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