N-Heterocyclic carbene catalyzed asymmetric [3 + 3] cycloaddtion of β,β-disubstituted, α,β-unsaturated carboxylic esters with 3-aminobenzofurans

Abstract

An N-heterocyclic carbene (NHC) catalyzed formal [3 + 3] cycloaddition reaction of β,β-disubstituted, α,β-unsaturated carboxylic esters with 3-amino benzofurans is doucumented, furnishing benzofuran fused δ-lactams bearing an all-carbon quaternary stereocenter...

Recent advances of N-heterocyclic carbenes in the applications of constructing carbo- and heterocyclic frameworks with potential biological activity

“…With the widespread application of NHC catalysts, reports regarding to synthesis of lactam compounds catalyzed by NHC are numerous. 61 2.7.1 Synthesis of b-lactam scaffold. In 2011, Ye and coworkers disclosed an efficient and atom-economic NHCcatalyzed [2 + 2] annulation reaction between N-sulnylanilines 93 and ketenes 92, achieving b-lactam scaffold in good yields with excellent enantioselectivities (Scheme 29).…”

“…With the widespread application of NHC catalysts, reports regarding to synthesis of lactam compounds catalyzed by NHC are numerous. 61 …”

N-Heterocyclic Carbene-Catalyzed [3 + 2] Annulation of 3,3′-Bisoxindoles with α-Bromoenals: Enantioselective Construction of Contiguous Quaternary Stereocenters

“…2 In fact, the construction of vicinal quaternary stereocenters has been described as "a daunting challenge in natural product synthesis". 3 The biggest challenge may come from the immense steric congestion imposed by the four carbon substituents. Although several methods have been developed to address this issue, further investigation on the development of efficient catalytic systems to construct contiguous quaternary stereocenters in a singe-step operation is still in high demand.…”

Stereoselective Access to Silicon-Stereogenic Silacycles via the Carbene-Catalyzed Desymmetric Benzoin Reaction of Siladials

“…So far, stereoselective access to silicon-stereogenic silanes via NHC catalysis remains a formidable task . Our group is keen on pursuing novel NHC-catalyzed methodologies to furnish optically pure and synthetically valuable molecules . We envisaged that once two identical formyl groups were installed at the proper positions of a prochiral tetrasubstituted silane, the chiral NHC catalyst would first chemoselectively attack the favored carbonyl carbon to generate the Breslow intermediate I .…”