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Most Requested Journal Articles 3Q04-Chemistry and Related Science

Following is one of the journal articles most requested by researchers using CAS online services.

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CAS subject entries for this document include: Arylation; Coupling reaction; Nucleophiles; and 1 additional concept.

CAPLUS COPYRIGHT 2004 ACS on STN

TITLE:	Dual role of nucleophiles in palladium-catalyzed Heck, Stille, and Sonogashira reactions
AUTHOR(S):	Jutand, Anny
CORPORATE SOURCE:	IUPAC Commission, Departement de Chimie, Ecole Normale Superieure, Paris, F-75231, Fr.
SOURCE:	Pure and Applied Chemistry (2004), 76(3), 565-576 CODEN: PACHAS; ISSN: 0033-4545
PUBLISHER:	International Union of Pure and Applied Chemistry
LANGUAGE:	English

ABSTRACT:
A review. In palladium-catalyzed Heck, Stille, or Sonogashira reactions, the nucleophiles-resp., alkenes, vinylstannanes or alkynes-are involved in carbopalladation or trans-metalation steps that follow the oxidative addn. of an aryl halide or triflate to a Pd0 complex. As soon as the nucleophiles possess a C=C or a C.tplbond.C bond capable of coordinating the Pd0 complex active in the oxidative addn., they play a dual role since they interfere in the oxidative addn. by a decelerating effect due to a partial coordination of the active Pd0 complex. Indeed, its concn. decreases due to the formation of either unreactive complexes (.eta.2-RCH=CH2)Pd0L2 (R = Ph, CO2Et, L = PPh3; R = Bu3Sn, L = AsPh3), (.eta.2-RCH=CH2)Pd0L2(OAc)- (R = Ph, L = PPh3), (.eta.2-R-C=CH)Pd0L2 (R = Ph, L = PPh3) or more slowly reactive complexes (.eta.2-R-C=CH)Pd0L2 (R = COEt, L = PPh3), (.eta.2-RCH=CH2)Pd0L2 (R = COMe, L2 = dppf). Whenever the oxidative addn. is faster than the ensuing carbopalladation or transmetalation, the decelerating effect of the nucleophiles in the oxidative addn. is in favor of a better efficiency for the catalytic cycle by bringing the rate of the fast oxidative addn. closer to that of the slow carbopalladation or transmetalation steps.

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