A number of stereoisomers of optically pure allylic alcohols with a trifluoromethyl group [CF3CH(OH)CH=CHR : R=Ph. C6H13] were prepared, utilizing the enantiotopic specificity of asymmetric hydrolysis of their acetates by hydrolases. Their absolute configurations were determined.
Preparation of phosphonium salt from (S)-trifluoropropene oxide and wittig type reactions
作者:Toshio Kubota、Masahiro Yamamoto
DOI:10.1016/s0040-4039(00)92255-x
日期:1992.4
triphenylphosphine in the presence of trifluoroacetic acid to afford the corresponding β-hydroxyalkyl phosphonium salt. Wittig type reaction of aldehydes with the salt under basic condition readily occurred to form optically active α-trifluoromethylated allylic alcohols. The trans-selectivity of these reactions were discussed.
A novel and expedient synthesis of optically active fluoroalkylated amino acids via palladium-catalyzed allylic rearrangement and Ireland–Claisen rearrangement
chiral α-fluoroalkylated mesylates with carboxylic acids in the presence of a palladium catalyst proceeded smoothly to give γ-fluoroalkylated allyl esters in excellent yields. The esters were subsequently subjected to Ireland–Claisen rearrangement without isolation, leading to the corresponding homochiral α-fluoroalkylated-β,γ-unsaturated amino acids in good yields.
A monoclonal antibody, elicited by a transition-state analogue for the hydrolysis of fluorinated esters, acted as an enzymelike catalyst for the preparation of chiral fluorinated compounds. The syntheses of (R)- or (S)-1-(fluoroalkyl)alkanols and an allylic alcohol possessing a trifluoromethyl group in high optical purity (> 98% enantiomeric excess (ee)) by antibody-derived reagents are described. The role of molecular recognition by antibody reagents and its importance to the preparation of optically pure materials is described. Significantly, it has been found that a fluoromethyl group on the stereogenic center or an acyloyl group enhanced the optical purity of the resultant products.
KITAZUME, TOMOYA;LIN, JENG TAIN;YAMAZAKI, TAKASHI;TAKEDA, MITSUNORI, J. FLUOR. CHEM., 43,(1989) N, C. 177-187