Process for preparing alkyl pyroglutamic acids

A method of producing a compound of formula (I):

• wherein
• R1, R2, R3, R4, R5, and R6 are independently selected from H, C1-C6 alkyl, C3-C8 cycloalkyl, C3-C8 cycloalkyl(C1-C6 alkyl), aryl, aryl(C1-C6 alkyl), heteroaryl, and heteroaryl(C1-C6 alkyl);
• and
• X is selected from C2-C20 alkylene, C2-C20 heteroalkylene, C2-C20 alkenylene, C2-C20 alkynylene, C3-C8 cycloalkyl, aryl, and —Y—Z—Y—;
• wherein each Y independently is C1-C10 alkylene, or C2-C10 heteroalkylene, and Z is aryl, heteroaryl, or heterocyclyl;
• the method comprising reacting a compound of formula (II):
• wherein R1, R2, R3, R4, R5, R6, and X are as defined above;
• with H2 in a solvent and in the presence of:
• a) a catalyst, b) at least about 0.1 molar equivalents of a nitro(C1-C10 alkane) optionally substituted with one or more OH groups, and c) at least about 0.1 molar equivalents of formaldehyde.