Diastereoselective Intramolecular Carbamoylketene/Alkene [2 + 2] Cycloaddition: Enantioselective Access to Pyrrolidinoindoline Alkaloids

A novel and highly diastereoselective intramolecular carbamoylketene/alkene [2 + 2] cycloaddition has been developed, and the methodology was successfully applied to the enantioselective syntheses of (−)-esermethole and Takayama’s intermediate for (+)-psychotrimine

Total Synthesis of Natural Enantiomers of Heliespirones A and C <i>via</i> the Diastereoselective Intramolecular Hosomi-Sakurai Reaction

A full account of the development of a novel type of the intramolecular Hosomi-Sakurai reactions of the substrates with a <i>p</i>-benzoquinone and an allylsilane moieties connected by an ether linkage is described. This transformation proceeds <i>via</i> 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 <i>Helianthus annuus</i> L. as allelochemicals

Total Synthesis of Natural Enantiomers of Heliespirones A and C <i>via</i> the Diastereoselective Intramolecular Hosomi-Sakurai Reaction

A full account of the development of a novel type of the intramolecular Hosomi-Sakurai reactions of the substrates with a <i>p</i>-benzoquinone and an allylsilane moieties connected by an ether linkage is described. This transformation proceeds <i>via</i> 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 <i>Helianthus annuus</i> L. as allelochemicals

Enantioselective Total Syntheses of Pygmaeocins B and C

The first enantioselective total syntheses of pygmaeocins B and C have been accomplished using an efficient and highly diastereoselective intramolecular Heck cyclization for the construction of a quaternary stereogenic center and the functionalized A-ring of the natural products as the key step