Patent ID: 7074937

Claim:
A method for making a compound of formula (I) wherein bonds a and b are single or double bonds, provided that one of a and b is a single bond and the other is a double bond; one of B 1 and B 2 is â€”CHR 5 â€”CHR 6 â€”C(Y)ZR 7 and the other is absent; B 3 is hydrogen; R 1 , R 2 , R 3 and R 4 are independently hydrogen, alkyl, alkenyl, aryl or aralkyl; or R 1 and R 2 , or R 3 and R 4 , combine with the carbon atom to which they are attached to form an alkyl or alkenyl ring; provided that at least three of R 1 , R 2 , R 3 and R 4 are not hydrogen Y is O or S; Z is O, S or NR 9 ; R 5 is hydrogen or C 1 â€“C 4 alkyl; R 6 is hydrogen or C 1 â€“C 4 alkyl; R 7 and R 9 are independently hydrogen, alkyl, alkenyl, aryl or aralkyl; said method comprising adding to an imidazolidinethione having formula CHR 5 â•CR 6 â€”C(Y)ZR 7 to form a reaction mixture; wherein the reaction mixture is substantially free of solvent.