Enantioselective synthesis of α-(3-pyrrolyl)methanamines with an aza-tetrasubstituted center under metal-free conditions.

Construction of a chiral methanamine unit at the C3 position of pyrrole is highly desirable; nevertheless, it remains challenging due to its intrinsic electronic properties. Herein, we present an operationally straightforward and direct asymmetric approach for accessing α-(3-pyrrolyl)methanamines under benign organocatalytic conditions for the first time. The one-pot transformation proceeds smoothly through an amine-catalyzed direct Mannich reaction of succinaldehyde with various -cyclic imines, followed by a Paal-Knorr cyclization with a primary amine.

Organocatalytic Asymmetric Construction of 2,6-Diazabicyclo-[2.2.2]octanes by Harnessing the Potential of an 3-Oxindolium Ion Intermediate.

Due to its structural complexity and intrinsic sensitivity of bridged aminal junction, 2,6-diazabicyclo[2.2.2]octane (2,6-DABCO) has remained a highly desirable target in synthetic chemistry.

Electrochemical Synthesis of 2-Aryl-3-(2-aminoaryl)quinoxalines via Oxidative Dearomatization/Ring-Opening/Cyclization Cascade Sequence of 2-Arylindoles with 1,2-Diaminoarenes.

A straightforward method has been developed to synthesize 2-aryl-3-(2-aminoaryl) quinoxalines from 2-arylindoles and 1,2-diaminoarenes under mild electrochemical conditions. The reaction proceeds through in situ generations of 2-arylindole-3-ones under electrochemical oxidative dearomatization of 2-arylindoles, followed by a ring opening-cyclization sequence with 1,2-diaminoarenes. A series of 2-aryl-3-(2-aminoaryl) quinoxalines have been prepared with moderate to good yields (up to 75%).

Enantioselective Direct Synthesis of C3-Hydroxyalkylated Pyrrole via an Amine-Catalyzed Aldol/Paal-Knorr Reaction Sequence.

Creating functionality with chirality at position C3 of pyrrole is challenging. An operationally simple organocatalytic method has been developed to generate functionality with a chiral tertiary/quaternary stereocenter at position C3 of pyrrole. The process proceeds through an amine-catalyzed direct aldol reaction of succinaldehyde with various acceptor carbonyls, followed by a Paal-Knorr reaction with a primary amine in the same pot.

Catalyst-free direct regiospecific multicomponent synthesis of C3-functionalized pyrroles.

An operationally simple catalyst-free protocol for the direct regiospecific synthesis of β-(C3)-substituted pyrroles has been developed. The enamine intermediate, generated from succinaldehyde and a primary amine, was trapped with activated carbonyls before the Paal-Knorr reaction in a direct multicomponent "just-mix" fashion to furnish pyrroles with overall good yields. Several C3-substituted -alkyl/aryl/H pyrroles have been produced under open-flask conditions with high atom economy and avoiding protection-deprotection chemistry.

Asymmetric Synthesis of Bridged -Heterocycles with Tertiary Carbon Center through Barbas Dienamine-Catalysis: Scope and Applications.

A direct aza-Diels-Alder reaction between 2-aryl-3-indolin-3-ones and cyclic-enones has been developed to access chiral indolin-3-one fused polycyclic bridged compounds. This method proceeds via proline-catalyzed Barbas-dienamine intermediate formation from various cyclic-enones such as 2-cyclopenten-1-one, 2-cyclohexene-1-one, and 2-cycloheptene-1-one, followed by a reaction with 2-aryl-3-indol-3-ones. Several indolin-3-ones fusing [2.