Reactivity and Diastereoselectivity in the Thermal and Lewis Acid-Catalyzed Diels−Alder Reactions of N-Sulfinylphosphoramidates1
The Journal of Organic Chemistry1998Vol. 63(5), pp. 1372–1378
Citations Over TimeTop 23% of 1998 papers
Abstract
The [4 + 2] cycloaddition reactions of N-sulfinylphosphoramidates, prepared from the corresponding phosphoramidates by treatment with N-(chlorosulfinyl)imidazole, and 1,3-cyclohexadiene were found to be diastereoselective in the absence (>90:10) and presence (>95:5) of Lewis acid. The sulfur configuration of the major adduct from the cycloaddition reaction has been established unambiguously by X-ray crystallography. The use of Lewis acids improved the diastereoselectivity and yield, as well as shortened reaction times. Based on the intermediacy of a tin chelate, and the absence of phosphoryl secondary orbital interactions, a mechanism for the cycloaddition reactions is discussed.
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