Regioselectivity of the ring opening in the reaction of phenyloxirane, (phenylmethyl)oxirane and (2-phenylethyl)oxirane with K−, K+(15-crown-5)2

The electron from potassium anion of K−, K+(15-crown-5)2 (1) is initially transferred to the aromatic ring of phenyloxirane and (phenylmethyl)oxirane. The oxirane ring is then opened exclusively in the α-position. Two dimeric products, i.e. dipotassium 2,3-diphenylbutane-1,4-dioxide and dipotassium 1,3-diphenylbutane-1,4-dioxide are formed in the case of phenyloxirane. A mixture of several potassium alkoxides involving 3-phenylpropoxide, 3-phenylallyloxide, tetraethylene glycoxide vinyl ether, and appropriate alcohols, i.e. 3-phenyl-1-propanol, 3-phenylallyl alcohol, and tetraethylene glycol vinyl ether, is obtained in the reaction of 1 with (phenylmethyl)oxirane. However, introduction of the second CH2 group into the substituent results in the β-opening of the oxirane ring in (2-phenylethyl)oxirane. Potassium 4-phenylbutane-2-oxide, and potassium tetraethylene glycoxide vinyl ether are the main reaction products in this case. Organometallic intermediates take part in all these processes.