Jan-Ji Lai

PHOTOOXYGENATION OF MESO-TETRAPHENYLPORPHYRIN METAL COMPLEXES

Abstract Cadmium(II), zinc(II), magnesium(II), and bis‐[thallium(I)] complexes of meso‐tetraphenyl‐porphyrin undergo unsensitized photooxygenation to yield a bilitriene derivative as the final product. The reaction has previously been shown to involve singlet oxygen (Matsuura et al., 1980); on the basis of mass spectrometry of products from 16O2 and 18O2 experiments, and characterization of the initial photoproduct, the reaction is shown to proceed by a mechanism in which one oxygen molecule adds to the metalloporphyrin to give a metallobilitriene. In the subsequent work‐up, demetalation and addition of two hydrogen atoms gives the final product.

Mechanism of photo-oxygenation of meso-tetraphenylporphyrin metal complexes

Abstract Photo-oxygenation of magnesium(II) meso -tetraphenylporphyrin (1a) to give open-chain benzoylbilitriene (2) is shown to proceed by way of a mechanism involving only one oxygen molecule.

Syntheses of chlorins from unsymmetrically substituted iron porphyrins

Mesohemin (1), deuterohemin (2), protohemin (3), 6,7-dipropylmesohemin (22), 1 -(2-carboxyethyl)meso-tetraphenylhemin (30), coprohemin-II (23), 2-acetyldeuterohemin (40), 2,4-diacetyldeuterohemin (41), and phyllohemin (51) were reduced to chlorins using sodium in isopentyl alcohol. Analytical and semi-preparative h.p.l.c. were used for separation, purification, and quantitation of isomers, which were then identified using 1H n.m.r. and mass spectroscopy. In the case of the mesochlorins (6), (8), (10), and (12), the ring-,D reduced product, (10), was identified by comparison with an authentic sample prepared from rhodochlorin dimethyl ester (14). The results cast doubt on some previous claims that reduction of unsymmetrical hemins gives only one, or at most two chlorin products, but they also elaborate the electronic and steric factors which control selectivity of reduction.