ChemInform Abstract: Highly Stereoselective Synthesis of Functionalized Pyrrolo[3,2‐c]quinolines via N‐Heterocyclic Carbene Catalyzed Cascade Sequence.

Abstract

Highly Stereoselective Synthesis of Functionalized Pyrrolo[3,2-c]quinolines via N-Heterocyclic Carbene Catalyzed Cascade Sequence. -Mannich-Michael-lactamization cascade reaction of aromatic aldimines and 2-bromoenals results in the formation of pyrroloquinolines with excellent diastereo-and enantioselectivities. -(YANG, Y.-J.; ZHANG, H.-R.; ZHU, S.-Y.; ZHU, P.; HUI*, X.-P.; Org. Lett. 16 (2014) 19, 5048-5051, http://dx.

Recent Advances of Catalytic Asymmetric 1,3-Dipolar Cycloadditions

“…Chiral N -heterocyclic carbene is also capable of promoting asymmetric 1,3-DC of azomethine ylides as reported by Hui and co-workers (Scheme ) . The cycloaddition of aromatic aldimines 301 having tosylamide at the ortho -position with 2-bromoenals was facilitated by the amino indanol-derived NHC 302 to give tricyclic compounds 303 with high diastereo- and enantioselectivities.…”

“…Chiral N-heterocyclic carbene is also capable of promoting asymmetric 1,3-DC of azomethine ylides as reported by Hui and co-workers (Scheme 133). 199 The cycloaddition of aromatic aldimines 301 having tosylamide at the ortho-position with 2-bromoenals was facilitated by the amino indanol-derived NHC 302 to give tricyclic compounds 303 with high diastereoand enantioselectivities. They proposed a stepwise mechanism for the cycloaddition, which proceeds via the Michael addition of α-imino malonate to the α,β-unsaturated azolium salt 304 generated from the aldehyde and the carbene.…”

N-Heterocyclic Carbene-Catalyzed Aza-Michael–Mannich–Lactamization Cascade for the Enantioselective Synthesis of Pyrazoloquinolin-3-ones

“…5b In 2014, Hui and coworkers demonstrated an elegant NHC-catalyzed cascade reaction of 2-bromoenals with tosyl-protected 2-amino aromatic aldimines for the enantioselective synthesis of pyrroloquinolone derivatives (Scheme 1, eq 1). 8 This domino process follows a Michael−Mannich−lactamization sequence to furnish the tricyclic products. Subsequently, the Chi group reported a related Michael−Mannich−lactamization sequence for the enantioselective functionalization of the benzylic sp 3 carbon leading to the synthesis of densely functionalized pyrrolidine derivatives (eq 2).…”