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Zirconium-catalyzed methylalumination of heterosubstituted arylethynes. Factors affecting the regio-, stereo-, and chemoselectivities.

ABSTRACT: The Zr-catalyzed methylalumination of heterosubstituted arylethynes containing O, S, Cl, and Si can proceed in high yields (>70%) and in a highly regio- and stereoselective manner (?98-99%), although SO(2)Ph, Br, and Cl in a benzylic position present serious chemoselectivity-related problems. The low regioselectivity of 60% initially observed with o-ethynylphenol (1a) has been elevated to ?98% through the use of either a catalytic amount of Zr(ebi)Cl(2) or Zr(2-Me-Ind)(2)Cl(2) or, more conveniently, the stoichiometric amount of ZrCp(2)Cl(2), ZrCp(2)MeCl, or ZrCp(2)Me(2) in conjunction with the use of a deficient amount (0.9 molar equivalent) of I(2) for subsequent iodinolysis.

SUBMITTER: Wang G

PROVIDER: S-EPMC2739592 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

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Zirconium-catalyzed methylalumination of heterosubstituted arylethynes. Factors affecting the regio-, stereo-, and chemoselectivities.

Wang Guangwei G Zhu Gangguo G Negishi Ei-Ichi EI

Journal of organometallic chemistry 20071001 21

The Zr-catalyzed methylalumination of heterosubstituted arylethynes containing O, S, Cl, and Si can proceed in high yields (>70%) and in a highly regio- and stereoselective manner (≥98-99%), although SO(2)Ph, Br, and Cl in a benzylic position present serious chemoselectivity-related problems. The low regioselectivity of 60% initially observed with o-ethynylphenol (1a) has been elevated to ≥98% through the use of either a catalytic amount of Zr(ebi)Cl(2) or Zr(2-Me-Ind)(2)Cl(2) or, more convenien ...[more]

PMID: 19746204

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