A method of making a compound of the formula: wherein R 1 is selected from the group consisting of C 1 -C 12 alkyl, C 2 -C 12 alkenyl, C 2 -C 12 alkynyl, C 2 -C 12 heteroalkyl, C 3 -C 12 cycloalkyl, C 2 -C 12 heterocycloalkyl, C 6 -C 18 aryl, and C 1 -C 18 heteroaryl; R 4 is selected from the group consisting of optionally substituted C 1 -C 12 alkyl, optionally substituted C 2 -C 12 alkenyl, optionally substituted C 2 -C 12 alkynyl, optionally substituted C 2 -C 12 heteroalkyl, optionally substituted C 3 -C 9 cycloalkyl, optionally substituted C 3 -C 9 cycloalkenyl, optionally substituted C 2 -C 12 heterocycloalkyl, optionally substituted C 2 -C 12 heterocycloalkenyl, optionally substituted C 6 -C 18 aryl, optionally substituted C 1 -C 18 heteroaryl, optionally substituted C 3 -C 9 cycloalkylC 1 -C 12 alkyl, C 2 -C 12 heterocycloalkylC 1 -C 12 alkyl, optionally substituted C 6 -C 18 arylC 1 -C 12 alkyl, optionally substituted C 1 -C 18 heteroarylC 1 -C 12 alkyl, optionally substituted C 6 -C 18 arylC 2 -C 12 heteroalkyl, optionally substituted C 3 -C 9 cycloalkylC 2 -C 12 heteroalkyl, optionally substituted C 6 -C 18 arylC 2 -C 12 heteroalkyl, optionally substituted C 2 -C 12 heterocycloalkylC 2 -C 12 heteroalkyl, and optionally substituted C 1 -C 18 heteroaryl C 2 -C 12 heteroalkyl, such that R 1 and R 4 are not the same; R 2 and R 3 are each independently selected from the group consisting of: H, and C 1 -C 12 alkyl; the method comprising reacting a compound of formula wherein R 1, R 2, and R 3 are as defined above and R 5 and R 6 are each independently C 1 -C 12 alkyl, with a primary amine of formula NH 2 R 4. R 1 is selected from the group consisting of C 1 -C 12 alkyl, C 2 -C 12 alkenyl, C 2 -C 12 alkynyl, C 2 -C 12 heteroalkyl, C 3 -C 12 cycloalkyl, C 2 -C 12 heterocycloalkyl, C 6 -C 18 aryl, and C 1 -C 18 heteroaryl; R 4 is selected from the group consisting of optionally substituted C 1 -C 12 alkyl, optionally substituted C 2 -C 12 alkenyl, optionally substituted C 2 -C 12 alkynyl, optionally substituted C 2 -C 12 heteroalkyl, optionally substituted C 3 -C 9 cycloalkyl, optionally substituted C 3 -C 9 cycloalkenyl, optionally substituted C 2 -C 12 heterocycloalkyl, optionally substituted C 2 -C 12 heterocycloalkenyl, optionally substituted C 6 -C 18 aryl, optionally substituted C 1 -C 18 heteroaryl, optionally substituted C 3 -C 9 cycloalkylC 1 -C 12 alkyl, C 2 -C 12 heterocycloalkylC 1 -C 12 alkyl, optionally substituted C 6 -C 18 arylC 1 -C 12 alkyl, optionally substituted C 1 -C 18 heteroarylC 1 -C 12 alkyl, optionally substituted C 6 -C 18 arylC 2 -C 12 heteroalkyl, optionally substituted C 3 -C 9 cycloalkylC 2 -C 12 heteroalkyl, optionally substituted C 6 -C 18 arylC 2 -C 12 heteroalkyl, optionally substituted C 2 -C 12 heterocycloalkylC 2 -C 12 heteroalkyl, and optionally substituted C 1 -C 18 heteroaryl C 2 -C 12 heteroalkyl, such that R 1 and R 4 are not the same; R 2 and R 3 are each independently selected from the group consisting of: H, and C 1 -C 12 alkyl; the method comprising reacting a compound of formula wherein R 1, R 2, and R 3 are as defined above and R 5 and R 6 are each independently C 1 -C 12 alkyl, with a primary amine of formula NH 2 R 4.