Author:
Cambie RC,Coddington JM,Milbank JBJ,Pausler MG,Rustenhoven JJ,Rutledge PS,Shaw GL,Sinkovich PI
Abstract
The enolates of (+)- and (-)- menthyl acetate, formed by transmetallation from lithium with chloro ( cyclopentadienyl )bis(1,2:5,6-di-O-isopropylidene-α-D-glucofuranosato-O3)titanium [ CpTi (DAGO)2Cl] (1), react with benzaldehyde from the Re-face with high stereoselectivities (95 and 92% diastereomeric excess) when 12-crown-4 is used during the transmetallation . Use of the chiral cyclopentadienyltitanium-α,α,αα,αα-tetraaryl-2,2-dimethyl-1,3-dioxolan-4,5-dimethanol (TADDOL) complex (3) gives lower diastereoselectivities (58 and 40%) but the Si -face of benzaldehyde is attacked preferentially. Transmetallation of the 2-methylprop-2-enyl moiety to CpTi (DAGO)2Cl gives an allyltitanium reagent (2) which reacts with benzaldehyde from the Re-face with 88% enantiomeric excess.
Cited by
9 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献
1. ChemInform Abstract: Stereoselective Titanium-Mediated Aldol Reactions of Menthyl Acetate Enolates, and Allylations with Benzaldehyde.;ChemInform;2010-08-20
2. Complexes of Titanium in Oxidation State iv;Comprehensive Organometallic Chemistry III;2007
3. Chloro(cyclopentadienyl)bis[3-O-(1,2∶5,6-di-O-isopropylidene-α-D-glucofuranosyl)]titanium;Encyclopedia of Reagents for Organic Synthesis;2001-04-15
4. Chloro(η5-cyclopentadienyl)[(4R,trans)-2,2-dimethyl-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4,5-dimethanolato(2−)-Oα,Oα′]titanium;Encyclopedia of Reagents for Organic Synthesis;2001-04-15
5. Asymmetric Aldol Reactions of Chiral Imidazolidinone Fischer Carbene Complexes;The Journal of Organic Chemistry;1994-11