Title

Ascorbic Acid Photoreductions of Zinc(II) Chlorophyll Derivatives: Access to Metal-Free Isobacteriochlorins

Document Type

Article

Publication Date

1-1-1988

Abstract

The products and resultant stereochemistry of the ascorbic acid/organic base photoreduction of zinc(II) chlorins were investigated. In the pheophorbide series the reaction is shown to give a cis-isobacteriochlorin 15 with a vinyl group external to the newly reduced ring. It is further demonstrated that under the basic reaction conditions this vinyl group is prone to double-bond migration toward the ring to give a stable ethylideneisobacteriochlorin 10. The biological implications of formation of the ethylidene moiety in this fashion are discussed. In addition, substituents were found to have a pronounced effect on the regiochemical selectivity of the reaction, as demonstrated by reduction of two rhodochlorin derivatives of methyl pheophorbide a. Demetalation of appropriate zinc(II) complexes yields the metal-free isobacteriochlorins 11, 13, and 15a. © 1988, American Chemical Society. All rights reserved.

Publication Source (Journal or Book title)

Journal of the American Chemical Society

First Page

2854

Last Page

2861

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