Catalyst-Controlled Diastereoselective Synthesis of Bridged [3.3.1] Bis(Indolyl)-Oxanes and Oxepanes via Desymmetrization of Bis(Indolyl)-Cyclohexadienones

Anion-Relay Double Aza-Michael-Michael Cascades to Enone-Tethered Cyclohexadienones: Access to an Intricate Bridged Ring System

An anion-relay double aza-Michael-Michael addition strategy has been reported for the synthesis of intricate scaffolds from enone-tethered cyclohexadienones and primary amines. This method discloses the base-catalyzed synthesis of highly valued bridged aza-tricyclic frameworks with a high level of product selectivity and stereoselectivity. Gram scale synthesis and synthetic transformation were shown to afford structurally diverse bridged aza-polycyclic amines. Control experiments and the kinetic profile were studied to determine a plausible reaction mechanism.

Synthesis of Azepinoindoles and Oxepinoindoles through Brønsted-Acid-Catalyzed Cyclization of an In Situ Generated Dihydrospiroquinoline Intermediate

We have developed a straightforward and efficient synthetic protocol to produce 5,6,7,12-tetrahydrobenzo[2,3]azepino[4,5-b]indole and 7,12-dihydro-6H-benzo[2,3]oxepino[4,5-b]indole derivatives under mild conditions. This annulation process involves the intramolecular cyclization of the in situ generated ketimine moiety via the formation of dihydrospiroindolequinoline, which serves as a key intermediate in the reaction pathway. Several control experiments and spectroscopic studies were performed to elucidate the underlying reaction mechanism.

Polycyclic Pyrazoles from Alkynyl Cyclohexadienones and Nonstabilized Diazoalkanes via [3 + 2]-Cycloaddition/[1,5]-Sigmatropic Rearrangement/Aza-Michael Reaction Cascade

An efficient method for the stereoselective synthesis of "all center substituted" polycyclic pyrazoles from alkynyl cyclohexa-2,5-dienones and nonstabilized diazoalkanes via sequential [3 + 2]-cycloaddition/[1,5]-sigmatropic rearrangement and aza-Michael reactions is reported. The developed process is highly regioselective and stereoselective. It employs a wide substrate scope to furnish structurally diverse linear and bridged [4.4.n.0] ring-fused pyrazoles in moderate to good yields. One-pot and gram-scale syntheses and synthetic transformations have also been showcased.