Partial syntheses of optically pure methyl bacteriopheophorbides c and d from methyl pheophorbide a

Abstract

A partial synthesis of the diastereomeric mixture of methyl pheophorbides 2 from the chlorophyll degradation product chlorin e6 trimethyl ester (4) is described. Compound 2 is related to band 6 of the bacteriochlorophylls c (Chlorobium chlorophylls, "660" series) and also to bacteriochlorophyll c" recently isolated from Chloroflexus aurantiacus. Separation of the R,S diastereomeric mixture [at the 2-(l-hydroxyethyl)group] is readily accomplished by using reverse-phase high-performance liquid chromatography (high-performance LC). Markownikoff hydration of methyl pyropheophorbide a (17) similarly gives the R,S diastereomeric mixture [16(R),16(S)] which can in turn be separated by high-performance LC. On account of Woodward's earlier total synthesis of optically pure chlorin e6 trimethyl ester (4), this work constitutes a formal total synthesis of the optically pure methyl pheophorbides of band 6 of the bacteriochlorophylls c (equivalent to methyl bacteriopheophorbide cs) and of band

Green Self‐Assembling Porphyrins and Chlorins as Mimics of the Natural Bacteriochlorophylls c, d, and e

“…Although excellent synthetic methodologies for annulation of such oxo-five-membered rings to porphyrins and chlorins have been developed, these involve several additional synthetic steps. [26] This structural element also forces the 13 1 -carbonyl group into co-planarity with the tetrapyrrolic macrocycle.…”

Facile Synthesis of 131-Oxo-porphyrins Possessing Reactive 3-Vinyl or 3-Formyl Group, Protochlorophyll-a/dDerivatives by 17,18-Dehydrogenation of Chlorins

“…This prompted us to check the reaction mixture carefully after treatment of 2 by HBr-AcOH and successive CH 2 N 2 which gave methyl bacteriopheophorbide-d (9) [3] (see Scheme 3). In silica gel column chromatography a minor red band was eluted after the major black band of 9.…”

“…Methyl pyropheophorbides-a/d (2, 3; IUPAC-IUB nomenclature recommends methyl 13 2 -demethoxycarbonyl-pheophorbides-a/d; the prefix 'pyro' denotes substitution of the 13 2 -methoxycarbonyl group for the hydrogen atom) are related to such chlorophylls. Compounds 2 and 3 have played important roles as key compounds for preparing models of photosynthetic light-harvesting antennae [3][4][5][6][7][8][9][10] and charge transfer reaction centres [11][12][13][14][15][16]. The corresponding chlorophyll-related porphyrins 5 and 6 (see Fig.…”

“…Typically, compounds 5 and 6 are useful for elucidation of the photoand enzymatic (dark) reduction of protochlorophyllide-a (17,18-didehydrochlorophyllide-a; the prefix 'proto' denotes removal of 17,18-dihydrogen atoms to make a double bond) to chlorophyllide-a [17] and also for preparation of naturally occurring peteroporphyrins without the 13 1 -oxo group which are metabolic products of chlorophylls [18] (see Scheme 1). 3-Vinyl and 3-formyl groups are reactive and a variety of chlorins have been prepared from methyl pyropheophorbides-a/d (2, 3) [3,6,[19][20][21]. Few porphyrins have been synthesized from the corresponding porphyrin 5 [22][23][24].…”

Chlorin p6 Cycloimides: Syntheses, Properties and Possible Fields of Application

“…В химии хлоринов эта реакция обычно применяется для синтеза 20-формилхлоринов. [46][47][48][49] Следует отметить, что 3-лактозилциклоимид 76 имел в 4-5 раз большую фотодинамическую активность, чем 8-и 12-лактозилпроизводные в экспериментах in vitro, а in vivo это соединение было наиболее активно по сравнению с конъюгатами N-гексилциклоимида с глюкозой 78 и галактозой 80.…”