Zeolite Molecular Sieve 4Å: A Reusable Catalyst for Fast and Efficient Conversion of Epoxides to Thiiranes with Thiourea

Various epoxides are readily converted to their corresponding thiiranes by thiourea/zeolite molecular sieve 4Å system in refluxing MeOH. All reactions were carried out within 12–25 min to give thiiranes in 80%–99% yields. The catalyst saves its catalytic activity for several times at this transformation. Stereospecific conversion of (R)-(+)-styrene oxide to (S)-(+)-styrene episulfide was achieved by this combination system.GRAPHICAL ABSTRACT Keywords: Epoxidethiiranethioureastereospecificzeolite molecular sieve 4Å AcknowledgementsThe financial support of this work was gratefully acknowledged by the Research Council of Urmia University.