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A full account of the development of a novel type of the intramolecular Hosomi-Sakurai reactions of the substrates with a p-benzoquinone and an allylsilane moieties connected by an ether linkage is described. This transformation proceeds via an addition-elimination sequence and provides the products with two stereogenic centers through a 1,3(or 1,4)-asymmetric induction in good to excellent diastereoselectivities. A reasonable mechanistic possibility for the reaction, determination of the stereochemistry for the product, and scope and limitation of the transformation are also discussed. The methodology developed here can successfully be applied to the enantiocontrolled total synthesis of the natural enantiomers of (-)-heliespirone A and (+)-heliespirone C, which have been isolated from sunflower Helianthus annuus L. as allelochemicals.

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An addition reaction of x-alkenylmagnesium bromide with aldehydes and consecutive oxidative cyclization with iodobenzene diacetate afforded brominated tetrahydrofuran in one pot. The reaction was also applicable to a one-pot synthesis of 2,5,5-trisubstituted tetrahydrofuran, lactone, and pyrazolidine using a ketone, carbon dioxide, and azodicarboxylate, respectively, as electrophiles. One-pot iodo-and chloro-cyclizations were also possible with alkenylmagnesium iodide and chloride.