A metal-free B(C6F5)3-catalyzed approach is developed for the disproportionation reaction of a series of indoles with various hydrosilanes, without any additives such as base and production of any small molecule such as dihydrogen. This boron catalyst system also exhibits excellent catalytic performance for practical application, such as catalyst loading as low as 0.01 mol % under solvent-free conditions, and a long-life catalytic performance highlighted by a constant catalytic activity being maintained and excellent yields being achieved for the desired products over 10 sequential additions of starting materials. On the basis of characterization of key intermediates through a series of in situ NMR reactions and detailed experimental data, we proposed a reaction mechanism which illustrated pathways for the formation of different products, including both major products and byproducts. Additional control experiments were conducted to support our proposed mechanism. Understanding the mechanism enables us to successfully suppress side reactions by choosing appropriate substrates and hydrosilanes. More importantly, the use of an elevated reaction temperature for continuous oxidation of the resulting indoline to indole makes the convergent disproportionation reaction an ideal atom-economical process. Near-quantitative conversions and up to 99% yields of C3-silylated indoles were achieved for various indoles with trisubstituted silanes, Ph3SiH (2b) or Ph2MeSiH (2d).

A highly effective method is developed for the C–C bond cleavage of lignin model compounds. The inert Cα–Cβ or Cα–Cphenyl bond of oxidized lignin model compounds was successfully converted to an active ester bond through the classic organic name reaction, Baeyer–Villiger (BV) oxidation, and thus acetal esters and aryl esters were produced in high yields (up to 99%) at room temperature. Next, K2CO3 catalyzed the alcoholysis of the resulting ester products at 45 °C, affording various useful chemical platforms in excellent yields (up to 99%), such as phenols and multifunctional esters. This method uses commercially available reagents, is transition-metal free and simple, but highly effective, and involves mild reaction conditions.

The strong Lewis acid Al(C6F5)3, in combination with a strong Lewis base N-heterocyclic olefin (NHO), cooperatively promotes the living ring-opening (co)polymerization of lactones, represented by δ-valerolactone (δ-VL) and ε-caprolactone (ε-CL) in this study. Medium to high molecular weight linear (co)polyesters (Mw up to 855 kg/mol) are achieved, and most of them exhibit narrow molecular weight distributions (Đ as low as 1.02). Detailed investigations into the structures of key reaction intermediates, kinetics, and polymer structures have led to a polymerization mechanism, in that initiation involves nucleophilic attack of the Al(C6F5)3-activated monomer by NHO to form a structurally characterized zwitterionic, tetrahedral intermediate, followed by its ring-opening to generate active zwitterionic species. In the propagation cycle, this ring-opened zwitterionic species and its homologues attack the incoming monomer activated by Al(C6F5)3 to generate the tetrahedral intermediate, followed by the rate-determining ring-opening step to regenerate the zwitterionic species that re-enters into the next chain propagation cycles. Owning to the living features and lack of transesterification side reactions possessed uniquely by this Lewis pair polymerization system, well-defined di- and triblock copolymers with narrow molecular weight distributions (Đ = 1.06–1.15) have been successfully synthesized using this method, regardless of the comonomer addition order.