Highly diastereoselective and enantioselective desymmetrization of α-substituted cyclohexadienones via NHC-catalyzed intramolecular Stetter reaction was realized. Amino-indanol derived triazolium salt bearing a C(6)F(5) group was found to be the optimal catalyst precursor in the intramolecular Stetter reaction furnishing tricyclic products bearing multi-stereocenters in up to 96% yield and >99% ee.
An enantioselective epoxidation of tryptophols followed by an intramolecular epoxide opening reaction was realized by chiral vanadium catalysts derived from C2 symmetric bis-hydroxamic acid (BHA) ligands. 3a-Hydroxyfuroindoline derivatives with up to 89% yield and 90% ee were obtained under mild reaction conditions.
The rapid and direct asymmetric synthesis of 3-(3a-indolyl)hexahydropyrroloindoline motifs is an extremely important part of the total synthesis of several alkaloid structures. Herein, an intermolecular, asymmetric cascade dearomatization reaction of indole acetamides with 3-indolylphenyliodonium salts has been developed. This protocol provides a straightforward access to 3-(3a-indolyl)hexahydropyrroloindolines bearing an all-carbon quaternary stereocenter at the C3 position of the indoline ring with high enantioselectivities. The utility of the protocol has been demonstrated by the formal asymmetric synthesis of folicanthine.
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