S. Okumoto et S. Yamabe, A computational study of base-catalyzed reactions between isocyanates and epoxides affording 2-oxazolidones and isocyanurates, J COMPUT CH, 22(3), 2001, pp. 316-326
Title reactions were investigated with ab initio calculations. Methyl isocy
anate and ethylene oxide were adopted as model reactants. The products, 2-o
xazolidones and isocyanurates, cannot be yielded without a base catalyst. T
he 2-oxazolidone may be produced by a dual S(N)2 reaction, where the cataly
st base (e.g., Cl-) is a nucleophile and a leaving group on the ethylene-ox
ide carbon. Isocyanurate is generated by the stepwise association of three
isocyanate molecules, where one of the molecules is initially linked with a
base. The six-membered ring isocyanurate is isomerized stepwise into the c
omponents isocyanate and 2-oxazolidone. A tetrahedral type of complex betwe
en the isocyanurate and a base-catalyzed ethylene oxide is the key intermed
iate for the isomerization. (C) 2001 John Wiley & Sons, Inc.