Journal of Organic Chemistry 2006-09-01

A new route for installing the isocyclic ring on chlorins yielding 13 1-oxophorbines.

Joydev K Laha, Chinnasamy Muthiah, Masahiko Taniguchi, Jonathan S Lindsey

Index: J. Org. Chem. 71 , 7049, (2006)

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Abstract

A new route to 13(1)-oxophorbines, the parent macrocycle of chlorophylls, begins with the synthesis of a 13-bromochlorin. Pd-mediated coupling of the latter with tributyl(1-ethoxyvinyl)tin and subsequent acidic hydrolysis afforded the 13-acetylchlorin (1). Treatment of 1 with NBS afforded the 15-bromo analogue in 70% yield. Pd-mediated alpha-arylation closed the isocyclic ring to give the 13(1)-oxophorbine (2) in 85% yield. Facile access to 13(1)-oxophorbines should enable a variety of spectroscopic studies and diverse applications.