SELECTIVE PALLADIUM-MEDIATED CARBON-OXYGEN BOND AND CARBON-SULFUR BOND-FORMING REACTIONS WHICH INVOLVE FUNCTIONALIZED C(SP)2-HYBRIDIZED HALIDES OR TRIFLATES AND C-SP-HYBRIDIZED HALIDES
R. Rossi et al., SELECTIVE PALLADIUM-MEDIATED CARBON-OXYGEN BOND AND CARBON-SULFUR BOND-FORMING REACTIONS WHICH INVOLVE FUNCTIONALIZED C(SP)2-HYBRIDIZED HALIDES OR TRIFLATES AND C-SP-HYBRIDIZED HALIDES, Tetrahedron, 53(3), 1997, pp. 1025-1044
(E)- and (Z)-2,3-dibromopropenoates were found to be able to react wit
h Bu(3)SnXR(1) (X = O,S: R(1) = alkyl, aryl) in NMP solution at 20 deg
rees C in the presence of Pd(PPh(3))(4) to give the corresponding 3-al
koxy, 3-arylthio and 3-alkylthio substituted products. Under similar c
onditions methyl (E)- and (Z)-3-bromopropenoate, methyl (Z)-3-iodo-2-o
ctenoate, 3-alkoxycarbonyl Substituted (cyclo)alkenyl triflates as wel
l as methyl 3-bromopropionate, were converted into the corresponding 3
-methylthio or 3-phenylthio substituted products when compounds Bu(3)S
nSR(1) (R(1) = Me. Ph) were used as nucleophiles. On the contrary. 2-b
romo substituted alpha,beta-unsaturated esters or lactones as well as
a 2-substituted alkyl 3-bromopropenoate did not undergo Pd-mediated su
bstitution reactions by treatment with Bu(3)SnOR(1) and 3-substituted
(E)-2,3-dibromopropenoates, and 3-substituted (Z)-3-iodopropenoates af
forded the corresponding alpha,beta-acetylenic esters, when reacted wi
th Bu(3)SnOR(1) in the presence of Pd(PPh(3))(4). A selective monosubs
titution reaction also occurred when 1,2-dibromobenzene, was reacted w
ith PhSSnBu(3) in toluene in the presence of Pd(PPh(3))(4). Finally. c
ompounds (E)- and (Z)-22a, which were prepared by Pd-mediated C-S bond
forming reactions, were used its direct precursors to some natural ca
rboxyamides. Copyright (C) 1996 Elsevier Science Ltd