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

Abstract

AbstractA 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, pK determination, UV and 1H‐NMR spectra.