Patent ID: 8168671

Claim:
A method of making a fused heterocycle, comprising: carboxylating the 3 position of a compound of formula I or a suitably protected derivative thereof to form a dicarboxylic acid compound; and converting the dicarbocylic acid compound to a fused heterocycle of formula (II) wherein X 1 is S, O, N—R 1 , or P—R 2 , wherein R 1 is hydrogen or a nitrogen protecting group, and R 2 is hydrogen or a phosphorus protecting group; X 2 is S, O, N—R 1 , or P—R 2 where R 1 and R 2 are as previously defined; and R is hydrogen, C 1 -C 20 alkyl, C 1 -C 20 haloalkyl, aryl, heteroaryl, C 1 -C 20 alkoxy, C 1 -C 20 haloalkoxy, aryloxy, —C 1 -C 10 alkyl-O—C 1 -C 10 alkyl, —C 1 -C 10 alkyl-O-aryl, nitro, halo, amino, or mono- or di alkyl amino.