Claims
- 1. 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.
- 2. A method of claim 1 wherein S-lactic acid methyl ester is used as the starting material and the Grignard reaction is conducted in the presence of more than one equivalent of bis(trimethylsilyl)acetamide.
- 3. A method of claim 1 wherein R-lactic acid methyl ester is used as the starting material and the Grignard reaction is conducted in the presence of more than one equivalent of bis(trimethylsilyl)acetamide.
- 4. The method of claim 1 wherein the compound of formula IV is represented by the formula. ##STR117##
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part application of International Application No. PCT/US94/14236, filed 20 Dec. 1994 which is a continuation-in-part of U.S. patent application Ser. No. 08/171,083, filed Dec. 21, 1993 and now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0539938A1 |
May 1993 |
EPX |
WO 8904829 |
Jun 1989 |
WOX |
9418978 |
Sep 1994 |
WOX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
171083 |
Dec 1993 |
|