A series of 1,3-propanediols and 1,4-butanediols were converted into cyclic sulfites with thionyl chloride. The cyclic sulfites were then oxidized to the corresponding cyclic sulfates with RuCl3 and Oxone® in water. This green oxidation method provided the cyclic sulfates in high yield and high purity under ambient conditions. Substituted heterocycles (azetidines and pyrrolidines) were thenprepared via a two-step process from the cyclic sulfates. Initially, the cyclic sulfates were treated with a series of primary amines to afford ammonio-alkyl sulfates in quantitative yield. The cyclization of the ammonio-alkyl sulfates was performed in aqueous media using microwave-assisted heating to yield the corresponding azetidines and pyrrolidines in good yields. The scope and limitations of this green synthetic approach for the construction of azetidines, pyrrolidines and other nitrogen heterocycles will be presented.

Microwave-assisted synthesis of nitrogen heterocycles from substituted cyclic sulfates

255th National Meeting (2018)

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