An environmentally benign and efficient method has been successfully developed to
generate S-(2H-chromen-4-yl) phosphorothioates from easily available 2-(3-hydroxyprop-1-ynyl)phenols
and O,O-diethyl phosphorothioic acid [(EtO)2P(O)SH] with water as the only byproduct. The reaction proceeds smoothly in moderate
to excellent yields. It is noted that (EtO)2P(O)SH acts not only as an acid promoter, but also as the nucleophile to attack the
allenic carbocation intermediate.
Key words
propargylic alcohols - phosphorothioic acids - phosphorothioates - cascade cyclization
- thiophosphates