Synthesis of 3-deazathiamine

An efficient ten-step synthesis of deazathiamine is described. The synthesis starts from commercially available alpha -acetyl-gamma -butyrolactone and proceeds via deamination of the key aminothiophene 6. The Gewald synthesis of thiophenes is shown to give a mixture of isomeric products with the unsymmetric ketone used here and so a modified procedure giving a single isomer is developed.