1,2‐Diaza‐1,3‐Butadienes: A New Approach to the Synthesis of Selenoheterocycles

1,2-Diaza-1,3-butadienes react easily with selenoureas to produce 2-selenazolin-4-one derivatives and with selenobenzamide to afford 2-selenazoline derivatives, the stereochemistries of which were determined. Whereas 2-selenazoline derivatives of 4R*,5R* configuration undergo aromatization under basic conditions, 2-selenazolin-4-ones, under different reaction conditions, appear to be attractive entry compounds to conjugated azoalkenes, 5,5-disubstituted selenazolin-4-ones, and spiro-condensed heterocyclic systems including selenazolinone rings. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)