
%0 Journal Article
%A Cambie, RC 
%A Coddington, JM 
%A Milbank, JBJ 
%A Pausler, MG 
%A Rustenhoven, JJ 
%A Rutledge, PS 
%A Shaw, GL 
%A Sinkovich, PI 
%T Stereoselective Titanium-Mediated Aldol Reactions of Menthyl Acetate Enolates, and Allylations With Benzaldehyde
%J Australian Journal of Chemistry
%D 1993/05/01
%V 46
%N 5
%P 583-591
%K 
%R https://doi.org/10.1071/CH9930583
%U https://www.publish.csiro.au/paper/CH9930583 
%X The enolates of (+)- and (-)- menthyl acetate, formed by transmetallation from lithium with chloro ( cyclopentadienyl )bis(1,2:5,6-di-O-isopropylidene-&#945;-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-&#945;,&#945;,&#945;&#945;,&#945;&#945;-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. 
