Syntheses of N-heterocyclic carbenes and intermediates therefor

A method of preparing an N-Heterocyclic Carbene, the method comprising:

• reacting an aniline of general formula XV:
• wherein each group R2 is the same and is selected from H, methyl, ethyl, n-propyl and
• wherein either R3 is H and R4 is alkyl that may be substituted, or
• each of R3,R4 are an independently selected alkyl that may be substituted;
• and wherein the groups Z1, Z2, and Z3 are H or a substituent independently selected from the group consisting of:
• —I, —CF3, —OR5, —R6 and -NR72;
• wherein each group R5,R6 or R7 is independently selected from the group consisting of:
• alkyl that may be unsaturated, substituted alkyl that may be unsaturated, aryl, substituted aryl, aralkyl and substituted aralkyl, with glyoxal to form a diimine of general formula XVI:
• cyclizing the diimine of structure XVI with paraformaldehyde, to form an imidazolium salt of structure XVII;
• wherein X− is an anion;
• and
• reacting the imidazolium salt of structure XVI with a base to form the corresponding N-Heterocyclic Carbene.