Biosynthesis inspired Diels-Alder route to pyridines: synthesis of the 2,3-dithiazolylpyridine core of the thiopeptide antibiotics.

Reaction of serine derived 1-alkoxy-2-azadienes with dehydroalanine derived dienophiles results in Diels-Alder reaction and aromatisation to give 2,3,6-trisubstituted pyridines, thereby establishing the viability of the proposed biosynthetic route to the pyridine ring of the thiopeptide antibiotics originally proposed by Bycroft and Gowland.