Process for preparing benzoic acid derivative intermediates and benzothiophene pharmaceutical agents

Abstract

Abstract The present invention provides a novel process for preparing a compound of formula I <CHEM> wherein R is C1-C4 alkyl; R<1> and R<2> each are independently C1-C4 alkyl, or combine to form piperidinyl, pyrrolidinyl, methylpyrrolidino, dimethylpyrrolidino, morpholino, dimethylamino, diethylamino, or 1-hexamethyleneimino; and n is 2 or 3; or a pharmaceutically acceptable salt thereof, comprising a) condensing (C1-C4 alkyl) 4-hydroxybenzoate with ethylene carbonate or propylene carbonate in the presence of a condensation catalyst and a moderately polar, water immiscible solvent having a high boiling point; b) reacting the product of step a), a compound of formula III <CHEM> wherein R and n are as defined above, with a leaving group donor; and c) reacting the product of step b), a compound of formula IV <CHEM> wherein R and n are as defined above and X is a leaving group, with a base selected from the group consisting of piperidine, pyrrolidine, methylpyrrolidine, dimethylpyrrolidine, morpholine, dimethylamine, diethylamine, and 1-hexamethyleneimine. The product of the above process, a compound of formula I, also is novel and is useful for the preparation of pharmaceutically active compounds of formula II, particularly via the following novel process <CHEM> wherein R is C1-C4 alkyl; R<1> and R<2> each are independently C1-C4 alkyl, or combine to form piperidinyl, pyrrolidinyl, methylpyrrolidino, dimethylpyrrolidino, morpholino, dimethylamino, diethylamino, or 1-hexamethyleneimino; and n is 2 or 3; or a pharmaceutically acceptable salt thereof, comprising a) condensing (C1-C4 alkyl) 4-hydroxybenzoate with ethylene carbonate or propylene carbonate in the presence of a condensation catalyst and a moderately polar, water immiscible solvent having a high boiling point; b) reacting the product of step a), a compound of formula III <CHEM> wherein R and n are as defined above, with a leaving group donor; c) reacting the product of step b), a compound of formula IV <CHEM> wherein R and n are as defined above; and X is a leaving group, with a base selected from the group consisting of piperidine, pyrrolidine, methylpyrrolidine, dimethylpyrrolidine, morpholine, dimethylamine, diethylamine, and 1-hexamethyleneimine; d) reacting the product of step c) with a compound of formula IV <MATH> wherein R<3> and R<4> are as defined above, or a pharmaceutically acceptable salt thereof; e) optionally removing the reaction product from step d) ; and f) optionally forming a salt of the reaction product from either step d) or step e).

Inventors

• 👤 Douglas Patton Kjell

Bibliographic Details