Catalytic methods for the synthesis of spirooxindoles, pyrroloindolines, and flavanones

Date
2016-01-01
Authors
Gerten, Anthony
Major Professor
Advisor
Levi M. Stanley
Committee Member
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Research Projects
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Chemistry
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Chemistry
Abstract

This thesis discloses catalytic, enantioselective dipolar cycloadditions to deliver new nitrogen-containing heterocycles and formal hydroarylations of olefins that have previously not been possible.

Catalytic, enantioselective, dearomative cycloadditions of stabilized, α-substituted azomethine ylides with 3-nitroindoles occur in the presence of a catalytic complex generated from Cu(OTf)2 and (R)-Difluorphos. These reactions set four contiguous stereocenters, two of which are fully substituted. Overcoming the barrier of breaking aromaticity, this catalyst system delivers pyrrolo[3, 4b]indoles with exoà ´-selectivity in moderate-to-good yields (39-85%) with high diastereoselectivity (up to 98 : 1 : 1 dr) and enantioselectivity (up to 96% ee).

Catalytic, enantioselective, dipolar cycloadditions of highly reactive nitrile imines with methyleneindolinones occur in the presence of a catalyst generated from Mg(NTf2)2 and a chiral aminoindanol-derived bisoxazoline ligand. The catalyst system designed overcomes a rapid competing background reaction to deliver spiro[pyrazolin-3,3′-oxindoles] in up to 98% yield and 99% ee.

Conjugate additions of arylboronic acids to challenging 2-alkylchromones occur in aqueous medium in the presence of a catalyst system generated from Pd(TFA)2 and 1,10-phenanthroline. This system overcomes the problem of competing protodeboronation and biaryl-forming reactions to deliver 2-alkyl-2-aryl-chromanones in up to 90% yield, providing a new and effective means of generating a fully substituted carbon center.

In all of these projects, effective catalyst design principles were established to overcome challenges that made these types of reactions previously impossible.

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