Referring to scheme 2, the compound of formula 1 (see scheme 1) is converted to a compound of the formula 6 by reaction with Horner-Emmons reagent which is prepared by reacting triethyl or other C1 -C3 alkyl phosphite with a halide of the formula R1 'CO2 CH2 X wherein R1 ' is C1 -C3 alkyl and X is a halogen including chloro and bromo.