achieved. So far the most economic catalyst system was developed for the addition of terminal alkynes to aromatic aldehydes in terms of ligand loading and enantioselectivity. Moreover, ligand 7a in combination with Ti(O-i-Pr)4 was found to be effective in promoting the addition reaction of an alkynylzinc reagent to unactivated simple ketones under very mild conditions. The corresponding chiral tertiary propargylic
A chiral copper complex, generated from a C 2-symmetric bis(hydroxycamphorsulfonamide) ligand (8 mol%) and Cu(OTf)2, has been discovered to effect high enantioselectivities in the addition of alkynylzinc to a series of simple ketones. The alkynylation of a variety of aromatic and aliphatic ketones resulted in excellent yields and enantioselectivities (83-98% ee). Even when the loadings of the catalyst is 5 mol%, up to 94% ee was obtained.
Highly Enantioselective Phenylacetylene Additions to Ketones Catalyzed by (<i>S</i>)-BINOL−Ti Complex
作者:Yifeng Zhou、Rui Wang、Zhaoqing Xu、Wenjin Yan、Lei Liu、Yongfeng Kang、Zhijian Han
DOI:10.1021/ol0485621
日期:2004.11.1
Ti(O(i)Pr)(4) is an effective chiral catalyst for the catalytic asymmetricaddition of alkynylzinc to unactivated simple ketones. Good to excellent enantioselectivities were achieved. No previous case has been reported successfully using BINOL to catalyze the addition of phenylacetylene to unactivated ketones, and thus the utility of BINOL in asymmetric catalysis is expanded.
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
Catalytic asymmetric addition of alkynylzinc reagents to ketones using polymer-supported chiral Schiff-base amino alcohols
作者:Chao Chen、Liang Hong、Bangzhi Zhang、Rui Wang
DOI:10.1016/j.tetasy.2007.11.040
日期:2008.2
Polymer-supported Schiff-base of optically active amino alcohols was used as chiralligands in the enantioselective addition of alkynylzinc to simple ketones. At a 10 mol % ligand loading, chiral propargylic alcohols with moderate to good ee values (up to 89%) were produced. The polymeric catalyst could be recycled many times and used for further reactions.