The mechanisms of reductive functionalization of CO 2 to formamide catalyzed by N-heterocyclic carbene (NHC) were comprehensively studied with DFT calculations. New activation mode with much lower energy barrier than those proposed before was discovered. In this reaction, NHC acts as neither a CO 2 nor a silane activator, but as a precursor of the real catalyst, i.e., the in situ formed ionic liquid [NHCH] + [Carbamate] -. In this loose contact ion pair, the negatively charged O atom of the carbamate anion becomes the new active site, and is free to do nucleophilic attack. When amine is absent, CO 2 will be converted into methanol. In this case, the NHC-CO 2 adduct is the real catalytic species, the active site shifted from the carbene C atom to the negatively charged O atom. These new activation modes follow a pattern of "S N 2@Si-Acceptor", in which the Si-H bond is activated via concerted backside S N 2 nucleophilic attack by the negatively charged O atom, and the leaving hydride is directly accepted by a free CO 2 molecule. The advantages of these new activation modes originate from the following points: (1) the ionic liquid [NHCH] + [Carbamate] -and NHC-CO 2 adduct are thermodynamically more stable than NHC; (2) the active site of the NHC catalyst is extended outside a lot. Consequently, the large steric effect between the NHC arms and the substrates in transition state can be avoided to some extent; (3) O atom has good silicon-affinity. In addition, a free CO 2 molecule, whose carbon atom is more electrophilic than those of the CO 2 moieties in NHC-CO 2 adduct and carbamate, acts as an efficient hydride acceptor.

Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.

Direct α‐functionalization of NH2‐free glycinates with relatively weak electrophiles such as α,β‐unsaturated esters still remains a big challenge in organic synthesis. With chiral pyridoxal 5 d as a carbonyl catalyst, direct asymmetric conjugated addition at the α‐C of glycinate 1 a with α,β‐unsaturated esters 2 has been successfully realized, to produce various chiral pyroglutamic acid esters 4 in 14–96 % yields with 81–97 % ee's after in situ lactamization. The trans and cis diastereomers can be obtained at the same time by chromatography and both of them can be easily converted into chiral 4‐substituted pyrrolidin‐2‐ones such as Alzheimer's drug Rolipram (11) with the same absolute configuration via tert‐butyl group removal and subsequent Barton decarboxylation.

The incorporation of Brønsted acid, thiourea anion binding, and transition metal catalysis enables an efficient method to synthesize chiral indolines via hydrogenation of indoles. Catalyzed by a rhodium/ZhaoPhos complex, asymmetric hydrogenation of unprotected indoles is performed smoothly with excellent enantioselectivities (up to 99% ee, up to 400 TON). Brønsted acid HCl activates indoles to form iminium ion intermediates. Mechanistic studies support the assumption that anion binding plays a crucial role as a secondary interaction. DFT calculations reveal an outer-sphere mechanism in this chemical transformation.