Efficient process to induce enantioselectivity in procarbonyl compounds
View Patent ↗The present invention provides an efficient method to induce the enantioselectivity in procarbonyl compounds using chiral organometallic complexes. The present invention also provides a method for producing chiral organometallic complexes using a chiral additive, achiral additive, a base and a metal salt.
1. A process for the preparation of an amino alcohol of formula
comprising the steps of
a) treating (1R,2S)—N-pyrrolidinyl norephedrine of formula
and trifluoroethanol (F 3 CCH 2 OH) with sodium hydride to obtain a sodium salt of (1R,2S)—N-pyrrolidinyl norephedrine and trifluoroethanol,
b) adding a zinc salt to the resultant sodium salts of (1R,2S)—N-pyrrolidinyl norephedrine and trifluoroethanol to obtain chiral (1R,2S)—N-pyrrolidinyl norephedrine and trifluoroethanol zincate complex of formula,
c) reacting a terminal alkyne compound of formula
with sodium hydride and MgCl 2 to give a cyclopropylacetylide complex of formula
d) mixing the chiral (1R,2S)—N-pyrrolidinyl norephedrine and trifluoroethanol zincate complex with the cyclopropylacetylide complex of formula
to obtain chiral organozinc complex of formula
e) mixing the chiral organozinc complex with a ketone of formula
to obtain the amino alcohol.
2. The process of claim 1 , wherein the zinc salt is zinc chloride, zinc bromide, zinc acetate, or zinc sulfate.