J. Kiji et al., PALLADIUM-CATALYZED CARBONYLATIVE COUPLING OF IODOBENZENE AND 2-METHYL-3-BUTYN-2-OL UNDER BIPHASIC CONDITIONS - FORMATION OF FURANONES, Journal of molecular catalysis. A, Chemical, 130(1-2), 1998, pp. 95-100
Carbonylative coupling of iodobenzene and 2-methyl-3-butyn-2-ol (4) in
aqueous NaOH/benzene was carried out by using Pd(OAc)(2)/Ph3P/Bu4PBr
(A) and Pd(OAc)(2)/Ph2P(m-C6H4SO3Na) (B) as catalyst. In sharp contras
t with a homogeneous Et3N solution, this biphasic solvent system gives
3-isopropylidene-5-phenyl-2(2H)-furanone (1) in a moderate yield. The
other carbonylated products are 2,2-dimethyl-5-phenyl-3(2H)-furanone
(2) and benzoic acid. The formation of 1 is explained by the following
sequential reactions; carbonylative coupling of iodobenzene with 4 to
form 4-hydroxy-4methyl-1 -phenyl-2-pentyn-1-one (6), hydrogenolysis o
f 6 to 4-methyl-1-phenyl-2,3-pentadien-1-one (8) and its cyclocarbonyl
ation to 1. Catalyst A gives 1 in a higher yield than B. (C) 1998 Else
vier Science B.V.