imide as a colorless oil ([a]: = +57 O , c = 1.2 in chloroform) which yielded theester (4) (m.p.114-115 "C, [alg=-35f 3 ' . c = 0.9 in chloroform) on hydrolysis (3 hours' boiling with 5 N HCI) and subsequent esterification with p-bromophenacyl bromide. No depression of melting point was observed with a mixture of (4) with an authentic sample[lbl, but such a depression was found with a mixture of ( 4 ) with rac44).
Optical rotation, chromatographic behavior, and IR spectrum (KBr) 1131 of (4) were as for the authentic material.
Treatment of bacteriomethylpheophorbide-a ( I ) with tetrachloro-o-benzoquinone in benzene at 25 "C led to 3.4-dehydro compounds (absorption spectrum); the reaction is. however, accompanied by oxidation at C-10[141. In order to avoid such oxidation we removed the methoxycarbonyl group from (I) by boiling it for 48 h in pyridine. The resulting bacteriopyromethylpheophorbide-a (2) reacted smoothly with tetrachloro-o-benzoquinone in benzene to give 2-acetyl-2-devinylpyromethylpheophorbide-a (3) whose physical properties (m.p., absorption spectrum, IR, NMR, mass spectrum), and particularly the ORD spectrum all agreed with those of a sample prepared from chlorophylla 1161.