Sheila I. Hauck

SYNTHESIS OF CYCLIC ENAMIDES BY INTRAMOLECULAR CYCLIZATION OF ACETYLENIC AMIDES

Abstract Cyclic enamides 12 of a type useful in the synthesis of naturally occurring chlorins, isobacteriochlorins, and corrins have been prepared by a process involving Nicholas-Schreiber condensation to afford acetylenic amides 13, followed by either n-Bu4NFue5f8 or LiA1(NHBn)4-catalyzed ring closure.

An improved synthesis of the C,D-ring pyrromethenone of phytochrome and phytochromobilin

Pyrromethenone 1b, the C,D-ring segment of both phytochrome (Pr) and phytochromobilin (PΦB) has been prepared in a highly efficient fashion beginning with 2-acetyl-butyrolactone (8). The key steps involved conversion of 8 to the Z-enol triflate 9, followed by Pdo catalyzed coupling with trimethylsilylacetylene, p-chlorophenylselenide ring opening, and amidation, to afford ring-D synthon 11 having the proper geometry and oxidation state for conversion to 1b.