Ytterbium-catalyzed dual intermolecular hydrophosphination: Synthesis of bis(phosphinyl)dienes and bis(alkenyl)phosphine oxides
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Dual intermolecular hydrophosphination of conjugated diynes with 2 equiv of diphenylphosphine was catalyzed by ytterbium complexes, Yb(η2- Ph2CNPh)(hmpa)3 (1) and Yb[N(SiMe3) 2]3(hmpa)2 (2), to give the corresponding 1,4-bis(diphenylphosphinyl)buta-1,3-dienes in high yields after oxidative work-up. Distribution of the four possible stereoisomers sharply depended on substituents of the substrates. (Z,Z)-Isomers were predominantly obtained from the disubstituted diynes, together with minor (Z,E)-isomers. On the other hand, the reaction of the terminal diynes provided major (E,Z) and minor (E,E)-butadienes. 1,4-Di-tert-butylbuta-1,3-diyne was exclusively converted to an allenic compound. Moreover, the dual hydrophosphination using phenyphosphine was also performed with 1 and 2. Thus, the reaction of 2 equiv of aromatic alkynes with PhPH2 and subsequent oxidation gave bis(alkenyl) phosphine oxides in preference of the (Z,Z)-stereoisomers.
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Copyright (c) 2005 Elsevier Ltd.
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Graduate School of Engineering