Phase-transfer catalysed (PTC) reactions of 1,1-dichloro-2-cyanocyclopropane with nucleophiles. Identification of intermediates

Abstract

An addition–elimination mechanism for PTC reactions of phenols with 1,1-dichloro-2-cyanocyclopropane (1) is supported by trapping of intermediate cyclopropenes 3 and 5. PTC reactions of 1 with a series of phenols 2a–d, thiophenol (2e), alcohols 2f,g and dithioles 11a,b led to formation of disubstituted cyanocyclopropanes 6a–d, 6e, 6f,g or spiroproducts 12a,b, respectively. Under acidic conditions or thermally, dialkoxycyclopropanes 6f,g or spirane 12a were transformed into alkyl 3-cyanopropionates 10f,g and ketene dithioacetal 13a.