Reacts with nucleophiles to give 2-substituted 2-methyl-1,3-propanediols; e.g. dialkylamines, on heating under pressure at 180o, give 2-(N,N-dialkylaminomethyl)-2-methylpropane-1,3-diols, and aqueous hydrogen halides give the corresponding 2-halomethyl compounds: Liebigs Ann. Chem., 365 (1973). Valuable protecting agent for carboxylic acids, introduced by Corey. The oxetane ester, formed from the acid chloride, rearranges with BF3 etherate to the bridged 2,6,7-trioxabicyclo[2.2.2]octane [OBO] orthoester, stable to strong bases and nucleophiles, e.g. Grignards, but readily cleaved by mild acid, followed by saponification of the ester: J. Am. Chem. Soc., 103, 4618 (1991); 106, 2735 (1984); Tetrahedron Lett., 23, 1651 (1982); 24, 5571 (1983); 27, 2199 (1986).