Cyclocondensation of oxalyl chloride with 1,2-glycols

Article abstract of DOI:10.1016/S0040-4020(01)81546-5

Oxalyl chloride reacts with a wide range of acyclic 1,2-glycols 1 in the presence of triethylamine to produce 1,3-dioxolan-2-ones 3 together with 1,4-dioxane-2,3-diones 2. Ethylene glycol (1d), monosubstituted ethylene glycols 1e, j-l, and erythro-1,2-disubstituted ethylene glycols 1f, m, o provide the cyclic carbonates 3 as the minor products, while the threo-compounds 1g, i, n, p, q and pinacol (1h) afford 3 as the main products. The formation of 3 may be rationalized in terms of stereoelectronically controlled cleavage of the conjugate base 17^- of the tetrahedral intermediates. The rate of the conformational change of 17^- into 18^- and the equilibrium constant between these conformers are proposed to be the major factors affecting the reaction pattern.