Cm. Marson et al., SYNTHESIS OF HYDROXYMETHYL LACTONES AND SPIROKETALS VIA CYCLIZATION OF EPOXY OXACARBENE COMPLEXES, Tetrahedron letters, 35(36), 1994, pp. 6717-6720
Metal acyls containing a terminal epoxide unit undergo cyclization wit
h SnCl4 to give oxacarbene complexes that can be cleaved to hydroxymet
hyl lactones using pyridine N-oxide.