Synthetic Approaches for the Construction of Five- and Six-Membered Silaazacycles

Controllable Si-C Bond Formation from Trihydrosilanes En Route to Synthesis of 1,4-Azasilinanes with Diverse Silyl Functionalities

A B(C6F5)3-catalyzed controllable inter/intra-/intermolecular Si-C bond formation process has been developed from trihydrosilane and dienamide with alkenes, anilines, or aryl iodides. A variety of 1,4-azasilinanes have been generated with diverse exo-cyclic heteroleptic disubstitutions on silicon, thereby expanding the range of silaazacyclic rings available for the discovery of silicon-containing drugs.

Scalable Synthesis of Silacyclohexanones and Ready Access to Silicon Building Blocks

A simple and efficient two-step method for the synthesis of silacyclohexanones starting from bis(bromoethylsilanes) using TosMIC is presented. The prepared silacyclohexanones were transformed to nine different heterocycles with silicon incorporation. In addition, the developed methodology was used for the synthesis of a sila analogue of the HDAC6 inhibitor tubastatin A.

Intramolecular Ring Expansion of 3-Silaazetidine with Alkynes Enabled by Pd-Catalyzed Si-C Bond Activation

An intramolecular ring expansion of in situ formed 3-silaazetidine with internal alkynes has been developed via Pd-catalyzed Si-C bond activation. The reaction gives rise to 6,5- and 6,6-fused bicyclic 1,3-azasilines, in which the silicon atom locates at the ring junction position.

(4 + 2) Annulation of Cl-NH3+CH2SiMe2CH2Cl and Propynones for the Synthesis of 1,3-Azasilinones

A useful 1,3-N,Si reagent (Cl^-NH₃⁺CH₂SiMe₂CH₂Cl) and its (4 + 2) annulation with propynones have been developed. The (4 + 2) annulation is promoted by NaHCO₃ via an intermolecular N-1,4-addition/intramolecular alkylation process, leading to 1,3-azasilinones in good yields. Diverse functionalization of the alkene, carbonyl, and nitrogen moieties on the 1,3-azasilinone has been demonstrated, showcasing the potential of the approach in the synthesis of bioactive molecules containing silaazacycles.

(3 + 2)-Annulation of 1,3-N,Si-tetraorganosilane reagents TsHNCH2SiBnR1R2 with arynes for efficient synthesis of 3-silaindolines

1,3-N,Si-Tetraorganosilane reagents TsHNCH2SiBnR1R2 were developed as robust synthons to prepare 3-silaindolines via a Cs2CO3-promoted (3 + 2)-annulation reaction with arynes.