title: Photoreduction of zinc 8-vinylated chlorophyll derivative to bacteriochlorophyll-b/g analog possessing an 8-ethylidene group.
abstract: When a pyridine solution of zinc methyl 8-vinyl-mesopyropheophorbide-a was irradiated with visible light in the presence of ethanol, ascorbic acid and diazabicylo[2.2.2]octane under nitrogen at room temperature, zinc (7R/S,8E)-8-ethylidene-bacteriochlorin was obtained via 1,4-hydrogenation. The 1,4-photoreduction is similar to the enzymatic reduction of 8-vinyl-chlorophyllides to (E)-8-ethylidene-bacteriochlorins in anoxygenic photosynthetic bacteria producing bacteriochlorophylls-b/g. The resulting zinc 8-ethylidene-bacteriochlorin was readily isomerized to the chemically more stable 8-ethyl-chlorin by further illumination. As a by-product, zinc 8-vinyl-7,8-cis-bacteriochlorin was slightly formed by photoinduced 1,2-hydrogenation of zinc 8-vinyl-chlorin.
authors.affiliation: Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan. tamiaki@fc.ritsumei.ac.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tamiaki
authors.forename: Meiyun
authors.initials: M
authors.lastname: Xu
authors.forename: Takuya
authors.initials: T
authors.lastname: Tanaka
authors.forename: Tadashi
authors.initials: T
authors.lastname: Mizoguchi
mesh_terms: D001429:Bacteriochlorophylls / Q000737:chemistry* / Q000378:metabolism; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D056831:Coordination Complexes / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry; D055668:Photochemical Processes; D014753:Vinyl Compounds / Q000737:chemistry* / Q000378:metabolism; D015032:Zinc / Q000737:chemistry*
chemical_list: D001429:Bacteriochlorophylls; D056831:Coordination Complexes; D014753:Vinyl Compounds; C107900:bacteriochlorophyll b; D002734:Chlorophyll; D008274:Magnesium; D015032:Zinc