Aufbau der Ligandsysteme des C, D‐Tetradehydrocorrins und Isobakteriochlorins durch Sulfidkontraktion. Kurzmitteilung

Abstract

Synthesis of C, D‐Tetradehydrocorrins and Isobacteriochlorins via Sulfide Contraction The reaction sequences shown in Schemes 4 and 5 illustrate the use of the sulfide contraction method for the synthesis of isobacteriochlorins and (metal free) C, D‐tetradehydrocorrins. The tetradehydrocorrin synthesis fills a gap in a spectrum of corrinoid (A → D) ring closures that ranges from A.W. Johnson 's oxidative (A → D)‐cyclizations to octadehydrocorrinoids on the one side to the photochemical 1, 19‐secocorrin → corrincycloisomerization on the other (Scheme 7) . Such a multiplicity of reaction paths towards corrinoids is of interest in connection with the problem of the origin of the corrin structure.