The asymmetric addition of lithium acetylides to carbonylcompounds in the presence of a chiral lithium binaphtholate catalyst was developed. A procedure involving the slow addition of carbonylcompounds to lithium acetylides improved the enantioselectivity. This reaction afforded diverse chiral secondary and tertiary propargylic alcohols in high yields and with good to high enantioselectivities.
BINOL−Salen-Catalyzed Highly Enantioselective Alkyne Additions to Aromatic Aldehydes
作者:Zi-Bo Li、Lin Pu
DOI:10.1021/ol0498139
日期:2004.3.1
BINOL-Salen compound (-)-1 can catalyze the addition of both aryl- and alkylalkynes to aromatic aldehydes at room temperature with high enantioselectivity (86-97% ee). The conditions for this catalytic process are both mild and simple. Unlike most other BINOL-based catalysts, using ligand (-)-1 not only avoids heating or cooling but also does not require the addition of Ti(O(i)Pr)(4).
Facile, Mild, and Highly Enantioselective Alkynylzinc Addition to Aromatic Aldehydes by BINOL/<i>N</i>-Methylimidazole Dual Catalysis
作者:Fei Yang、Peihua Xi、Li Yang、Jingbo Lan、Rugang Xie、Jingsong You
DOI:10.1021/jo0707535
日期:2007.7.1
acid/base catalytic system, generated from N-methylimidazole (NMI), (R)-1,1‘-bi-2-naphthol [(R)-BINOL], and Ti(OiPr)4, effectively catalyzes the enantioselective alkynylation of aldehydes in the presence of Et2Zn in good yields and excellent enantioselectivities of up to 94% ee at room temperature. The mild reaction conditions make it possible to use functional alkynes in this asymmetric addition.
Enantioselective alkynylation of aldehydes and ketones was accomplished using trimethoxysilylalkynes as alkynylating reagents and lithium 3,3′-diphenylbinaphtholate as a catalyst. Optically active propargylic alcohols were obtained in good to high chemical yields and enantioselectivities. Alkynylation of acetylpyridines afforded biologically active pyridyl propargylic alcohols in good enantioselectivities
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).