Pteridines. Part LXXXV. Chemical synthesis of deoxysepiapterin and 6‐acylpteridines by acyl radical substitution reactions

Abstract

Abstract A new synthesis of deoxysepiapterin ( 2 ), one of the two yellow eye pigments of the Drosophila mutant sepia , is described. The synthetic approach makes use of a homolytic nucleophilic acylation of 7‐(alkylthio)pteridine derivatives ( 11, 13, 15, 18, 20 ) leading to the corresponding 6‐acyl derivatives ( 21–27 ). Desulfurizations have been achieved for the first time in the pteridine series using Raney ‐Co, Raney ‐Cu, or CuAl alloy in alkaline medium. Besides cleavage of the C(7)S bond, further reductions of the CO group at C(6) and the C(7)N(8) bond are detected as side reactions leading to 6‐(1‐hydroxyalkyl) ( 34, 35, 42, 43 ) and 6‐acyl‐7,8‐dihydro derivatives ( 2, 36, 37 ), respectively, The newly synthesized compounds have been characterized by elemental analysis, p K determination, UV and 1 H‐NMR spectra.