Tetrahydrofuran antifungals

A method of making compounds of the formula I ##STR112## wherein X is independently both F or both Cl or one X is independently F and the other is independently Cl, and wherein the absolute stereochemistry at each asterisk carbon (*) is same i.e., S,S or R,R substantially free of S,R or R,S and wherein S or R-lactic acid ester is contacted with pyrrolidine and a hydroxy protecting group reagent converted into the corresponding lactic acid amide, which is selectively reduced to the corresponding propionaldehyde and then converted into the corresponding N-formylaminopropanimine which comprises:

• (a) reacting the N-formylaminopropanimine of the formula II ##STR113## with ethylmagnesium bromide under Grignard reaction conditions sufficient to produce a compound of the formula III ##STR114## wherein the absolute stereochemistry induced at the double asterisk carbon (**) is substantially the same as that at the single asterisk carbon and wherein PG is a hydroxy protecting group and (b) reacting the compound of formula III with a compound of formula IV ##STR115## in the presence of 1,8-diazabicycloundec-7-ene and at elevated temperatures for a time sufficient to produce the compound of formula V ##STR116## and (c) reacting the compound of formula V with a catalytic amount of Pd black on carbon in the presence of formic acid to produce after purification the compounds of formula I.