Bonelline

With the discovery and structure elucidation of bonellin (1) and factor I (2), both naturally occurring chlorins. the systematic investigation of total synthetic approaches leading to these natural products and other chlorins was induced.4... 

Bonellin Mononitrile Methyl Ester (7 e) Typical Procedure 71 ... 

Intramolecular Friedel-Crafts acylation has been observed with bonellin dimethyl ester (20).53 The reaction proceeds in contrast to corresponding porphyrins, very smoothly with concentrated sulfuric acid because the propanoic acid side chain at the sp3 center is located above the macrocyclic ring system and therefore can better fulfill the stereoelectronic requirements for the ring-closure reaction. The ring closure is accompanied by racemization in the product 21. 

Dihematoporphyrin derivatives (DHPD) have been introduced in tumor therapy [201]. These derivatives develop high cytotoxicity in light-sensitized cells. Although structurally, the active component appears to be a dimer [202], some suggest it to be the ester [203], and others the ether and the ester [204], it is clear that the cytotoxic complexation occurs via exciplex-ation [42]. Several other esters (mesochlorine and bonellin) of DHPD ether are claimed [205] to be five times more lethal than DHPD. 

Cyclization to the benzo[c]phenanthridine (127) competes with rearrangement to the ring-expanded product (128) on irradiation of the amine oxide (129). A practical synthesis of the chlorin macrocycle (130) has been developed by irradiation of the seco-compound (131) in tetrahydrofuran containing TFA and Hiinig s base this is thought to take place by photocyc-lization of the ISrr-tautomer (132), followed by elimination of methanol. Analogous approaches have been employed in the syntheses of ( )-bonellin dimethyl ester and 20-methyl- and 20-cyano-isobacteriochlorins. " ... 

Sex determination can also be regulated by free chemical mediators. This is particularly the case for the worm Bonellia fuliginosa, whose larvae produce only male parasites if they develop on an adult female. Sex is determined by the production of bonelline, a pheromone manufactured by this female (Mackie and Grant, 1974). 

Progress in the synthesis of chlorophylls and bacteriochlorophylls (di- and tetra-hydro porphyrins) has been relatively slow, but the recent isolation of new reduced porphyrins, such as the physiologically active marine pigment bonellin" and sirohydrochlorin (an intermediate in vitamin B12 biosynthesis) is likely to stimulate attempts to synthesize these compounds directly from partially reduced open chain precursors rather than by reduction of preformed porphyrins (see Section 11). Considerable progress has already been made in the development of new methods for synthesizing the partially reduced bile pigments (Section 9). 

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