A large-scale synthesis of 3, 4, 5-tri-0-acetyl-2, 6-anhydro-L-mannono-and-D- gulonothioamides (5, 6) has been achieved from the corresponding nitriles. The Hantzsch reaction of (5) or (6) with ethyl bromopyruvate afforded the expected thiazoles (7.8) only in a low yield along with furan derivatives (9-11), the formation of which is rationalized by an acid- catalysed rearrangement-elimination process. The some Hantzsch reaction in the ...