Organocatalytic Asymmetric Synthesis of Carbo- and Oxacyclic Seven-Membered Bridged Biaryls via Nucleophile-Dependent Switchable Domino Processes
Namrata Kotwal, Tamanna, Avtar Changotra, Pankaj Chauhan
Abstract
We disclose herein a highly diastereo- and enantioselective divergent synthesis of seven-membered biaryl-bridged carbo- and oxacyclic frameworks by utilizing the catalytic ability of bifunctional hydrogen-bonding squaramide organocatalysts. Starting with the same biaryl substrate bearing two distinct acceptor sites and by choosing soft or hard nucleophiles, we readily accessed the dibenzocycloheptanes or 5,7-dihydrodibenzo[ c,e ]oxepines bearing multiple elements of chirality via a domino 1,4/1,2-addition or 1,2/oxa-Michael addition sequence, respectively.
Topics & Concepts
SquaramideChemistryEnantioselective synthesisBifunctionalNucleophileDominoCatalysisAcceptorStereochemistrySubstrate (aquarium)Combinatorial chemistryOrganocatalysisSequence (biology)Organic chemistryGeologyOceanographyPhysicsBiochemistryCondensed matter physicsAxial and Atropisomeric Chirality SynthesisMolecular spectroscopy and chiralityChemical synthesis and alkaloids