Diastereoselective Synthesis of Spiro[pyrazolone-4,3 '-tetrahydrothiophenes] via a Sulfa-Michael/Aldol Domino Reaction

摘要

A new approach for the diastereoselective synthesis of spiro[pyrazolone-4,3'-tetrahydrothiophenes] was developed. The N,N-diisopropylethylamine-catalyzed reaction of arylidenepyrazolones with in situ generated 2-sulfanylacetaldehyde provides the corresponding spiro-heterocycles via a domino sulfa-Michael/aldol reaction in 42-98% yield and 3: 2: 1 to 20: 1 d.r. under mild reaction conditions.