Patent ID: 8754197

Claim:
A method for preparing a compound of the formula: where R 1 , and R 3 are selected from the group consisting of H, CH 3 , CH 2 CH 3 , and CH(CH 3 ) 2 ; R 4 is H and R 2 is: where R 5 , R 6 , R 7 and R 8 are independently hydrogen or C 1 to C 4 alkyl; or the esters or pharmaceutically acceptable salts thereof, comprising: converting a compound of one of the following formulas: to a diazonium salt; reacting the diazonium salt with a compound of one of the following formulas: hydrolyzing the nitrile or amide group to form a carboxylic acid group, and optionally forming an ester or pharmaceutically acceptable salt of one or more of the carboxylic acid groups.