Regio- and stereoselective modification of cytosine with cyanopropargylic alcohols

Cyanopropargylic alcohols (4-hydroxyalk-2-ynenitriles) add cytosine at the triple bond under mild conditions (3–5 mol% K₂CO₃, DMF, 20–25°C, 2–3 h) to afford regio- and stereoselectively the Michael adducts, (Z)-3-[4-amino-2-oxo-1(2H)-pyrimidinyl]-4-hydroxy-4-alkylalk-2-enenitriles, in80–88% yield.