Enantioselective Alkyne Addition to Aliphatic, Aromatic, and Vinyl Aldehydes Using Zn, iPrI, H8BINOL, and Ti(OiPr)4
摘要:
A new catalytic system based on the readily available Zn, (PrI)-Pr-i, H8BINOL, and Ti((OPr)-Pr-i)(4) has been developed which avoids the use of pyrophoric ZnEt2. It can effectively catalyze the reaction of various terminal alkynes with aromatic, aliphatic, and vinyl aldehydes to generate chiral propargylic alcohols at room temperature with up to 98% yield and 98% enantiomeric excess. This new system signifciantly expands the substrate scope of the previously reported system using Zn, EtI, BINOL, and Ti((OPr)-Pr-i)(4).
Chiral Macrocycle-Catalyzed Highly Enantioselective Phenylacetylene Addition to Aliphatic and Vinyl Aldehydes
作者:Zi-Bo Li、Tian-Dong Liu、Lin Pu
DOI:10.1021/jo070091j
日期:2007.6.1
The 1,1‘-binaphthyl macrocycle (S)-2 is found to be an excellent catalyst for the alkyne addition to aldehydes. In the presence of (S)-2 (20 mol %) and Me2Zn (2 equiv) in THF at room temperature, the addition of phenylacetylene to linear or branched aliphatic aldehydes and vinylaldehydes gave various propargylic alcohols with 89−96% ee.
Highly Enantioselective Phenylacetylene Additions to Both Aliphatic and Aromatic Aldehydes
作者:Ge Gao、David Moore、Ru-Gang Xie、Lin Pu
DOI:10.1021/ol026921r
日期:2002.11.1
The readilyavailable and inexpensive BINOL in combination with Ti(O(i)Pr)(4) is found to catalyze the reaction of an alkynylzinc reagent with various types of aldehydes including aliphaticaldehydes, aromaticaldehydes, and other alpha,beta-unsaturated aldehydes to generate chiral propargyl alcohols with 91-99% ee at room temperature. No previous chiral catalysts have exhibited such a broad scope
Several C-3-symmetric trialkanolamines can be efficiently obtained via molecular sieve-assisted epoxide ring opening with ammonia in high yields (up to 90%) and regioselectivity up to 100%. These trialkanolamines were effective for the asymmetric alkynylation of aldehydes and the propargyl alcohols were obtained in high yields (up to 92%) and high enantiomeric excesses (up to 95%). The H-1 NMR spectra support that there could be a complex mixture of polynuclear Ti(IV)-based species form from the interaction of Ti(IV) with ligand. (C) 2014 Elsevier B.V. All rights reserved.