Pyrroles and related compounds. Part XXXI. Porphyrin ketones

Abstract

The synthesis of 4,6,8-triethyl-2-methoxycarbonyl-1,3,5,7-tetramethylporphin (2a)via the a,c-biladiene route is reported. Treatment of the corresponding acid chloride (2c) with diazomethane afforded the diazo-ketone (2d) which furnished the porphyrin ketone (2e) when treated with triheptylborane. With sodium borohydride, the alcohol (2f) was obtained, thereby opening up a definitive route to the hydroxyalkyl type of substituent which is favoured in some proposals for the structure of haem-a.