Catalytic enantioselective addition of terminal alkynes to aromatic aldehydes using zinc-hydroxyamide complexes
作者:Gonzalo Blay、Luz Cardona、Isabel Fernández、Alícia Marco-Aleixandre、M. Carmen Muñoz、José R. Pedro
DOI:10.1039/b911592g
日期:——
A mandelamide ligand, derived from (S)-mandelic acid and (S)-phenylethanamine, catalyzes the addition of aryl-, alkyl- and silyl-alkynylzinc reagents to aromatic and heteroaromatic aldehydes with good yields and good to high enantioselectivities.
Cooperative Catalysis of Metal and OH⋅⋅⋅O/sp<sup>3</sup>-CH⋅⋅⋅O Two-Point Hydrogen Bonds in Alcoholic Solvents: Cu-Catalyzed Enantioselective Direct Alkynylation of Aldehydes with Terminal Alkynes
with a transition‐metal center in alcoholic solvents for enantioselective catalysis. Copper(I) complexes with prolinol‐based hydroxy amino phosphane chiral ligands catalytically promoted the directalkynylation of aldehydes with terminal alkynes in alcoholic solvents to afford nonracemic secondary propargylic alcohols with high enantioselectivities. Quantum‐mechanical calculations of enantiodiscriminating
Asymmetricalkynylation of both aromatic and aliphatic aldehydes using catalytic amounts of In(III)/BINOL is described. Dual activation of both substrates due to the "bifunctional character" of the indium(III) catalyst enables a broad range of substrate generality with high enantioselectivity (83 to >99% ee).
Mandelamide−Zinc-Catalyzed Enantioselective Alkyne Addition to Heteroaromatic Aldehydes
作者:Gonzalo Blay、Isabel Fernández、Alícia Marco-Aleixandre、José R. Pedro
DOI:10.1021/jo0610255
日期:2006.8.1
The (S,S)- mandelamide III catalyzes the additions of both aryl- and alkylalkynylzinc reagents to heteroaromatic aldehydes with good yields and enantioselectivities up to 92%. This catalyst is easily prepared in a one-step procedure, and both enantiomers are available. Unlike most other described methods, using this catalyst does not require the addition of Ti((OPr)-Pr-i)(4).
Direct and Stereospecific Synthesis of Allenes via Reduction of Propargylic Alcohols with Cp<sub>2</sub>Zr(H)Cl
作者:Xiaotao Pu、Joseph M. Ready
DOI:10.1021/ja8035527
日期:2008.8.1
Allenes can be synthesized via the direct SN2' addition of hydride to propargylicalcohols. Previous examples of this approach, however, have involved harsh reaction conditions and have suffered from incomplete transfer of central chirality to axial chirality. Here we show that Cp2Zr(H)Cl can react with the zinc or magnesium alkoxides of propargylicalcohols to generate allenes in good yield and in