SYNTHESES OF OXYGEN ANALOGS OF SULFHEME-A AND SULFHEME-C

Syntheses of metal-free oxygen analogues of the sulfhemes-A and -C fro m protoporphyrin-IX dimethyl ester 1 are presented. Oxasulfporphyrin-C dimethyl ester 5 is obtained by intramolecular displacement of a prim ary tosylate by a tertiary hydroxyl in an appropriately constructed pr ecursor 18, or by surface-catalyzed rearrangement of the epoxide-beari ng oxasulfporphyrin-A dimethyl ester 23. Compound 23 is in turn prepar ed by Mitsunobu type internal;dehydration of the precursor 12. The met hodology is then successfully extended to more symmetric porphyrin sys tems. Compounds 23, 25, 46, and 61/62 are the first porphyrin epoxides to be synthesized.