Processes for the preparation of alpha-hydroxy esters by esterification of alpha-hydroxy acids

A method of preparing a compound of Formula (I):

• wherein
• R1 is chosen from H;
• C1-4 alkyl optionally substituted with —OH, —SH, —S—C1-4 alkyl, —CONH2, —NRaRb, or guanidino;
• phenyl optionally substituted with —OH or C1-4 alkyl;
• indolyl;
• and imidazolyl;
• wherein Ra and Rb are each independently H or C1-4 alkyl;
• and
• R2 is C1-8 alkyl or C4-7 cycloalkyl;
• comprising a) reacting at room temperature a compound of formula RxC(O)Cl with a compound of formula R2OH to form a reagent of Formula (A):
• and to form in-situ an acid catalyst;
• wherein Rx is chosen from H, C1-4 alkyl, and CH2—CH—;
• and
• b) reacting, at a temperature of 80° C. to 90° C., a compound of Formula (II):
• with the reagent of Formula (A) in the presence of the in-situ generated acid catalyst.