Reaction control of cyclic ethers by new versatile catalysts and its application

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The cycloaddition of oxiranes with heterocumulenes such as isocyanates and carbodiimides has been ardently investigated. Although a variety of catalysts for this reaction have been reported, the problems such as low yields and severe reaction conditions have not been resolved as yet. Now, this our project has given one resolution in terms of developing novel catalysts; organotin iodide-Lewis base complexes(1), organotin iodide-onium halide salts complexes(2) and tetraphenylstibonium iodide(3). These catalysts very effectively promoted the cycloadditon of under very mild conditions to produce many kinds of heterocyclic compounds in excellent yield. Advantages and features of these catalysts are as follows(a-c);(a) The cycloadditions complete within few hours at room temperature.(b) The catalysts 1 and 2 selectively promote the -cleavage cycloaddition of monosubstituted oxiranes. On the contrary, the catalyst 3 promotes the -cleavage one which has been unsuccessful by conventional catalysts at all. The both reactions could be carried out for the same reactants under similar reaction conditions, and so these catalysts can be used compensationally.(c) These catalysts are so nearly neutral that the oxiranes bearing labile substituents are applicable to this cycloaddition.