Synthesis of six-membered silacycles by borane-catalyzed double sila-Friedel–Crafts reaction

Abstract

We have developed a catalytic synthetic method to prepare phenoxasilins. A borane-catalyzed double sila-Friedel–Crafts reaction between amino group-containing diaryl ethers and dihydrosilanes can be used to prepare a variety of phenoxasilin derivatives in good to excellent yields. The optimized reaction conditions were also applicable for diaryl thioethers to afford their corresponding six-membered silacyclic products. The gram-scale synthesis of a representative bis(dimethylamino)phenoxasilin and the transformation of its amino groups have also been demonstrated.

Convenient Synthesis and Biological Evaluation of Bis(indolyl)methane Alkaloid and Bis(aryl)alkanes Derivatives with Anti-cancer Properties

“…Therefore, a demand of milder, wider application and metal-free catalytic methods for obtaining various BIMs or Bis(aryl)alkanes derivatives is of great interest and importance. B(C6F5)3, one component of FLPs (Frustrated Lewis Pairs, FLPs), 16 has been successfully applied to several important organic conversions as a Lewis acid catalyst without any metal ion, including hydrogenation, 17 hydrosilylation of unsaturated organic functional groups, 18 dehydrogenation, 19 polymerization 20 and other transformations. 21 In general, B(C6F5)3, as a strong Lewis acid, is able to activate the imine via πcoordination to the C-N double bonds.…”

Synthesis and Properties of Cyclic π-Conjugated Molecules and Their Dication and Monoradical Cation

“…We recently reported the synthesis of five-, six-, and sevenmembered cyclic π-conjugated molecules by double Friedel− Crafts reaction of electron-rich biaryl compounds with Meldrum's acid derivatives as methylenation reagents. 11,12 Using this reaction, cyclic π-conjugated molecules 3a and 3b were obtained in 39% and 34% yields, respectively, from amino group-substituted 1,2-bis(arylethynyl)benzene 1a or 1b and Meldrum's acid derivative 2 (Scheme 1). It is interesting that the cyclic structures of 3a and 3b were formed in spite of a long-distance between two carbon atoms of the two aromatic rings, which are the reaction sites of 1a and 1b (1a: 4.331 Å by density functional theory (DFT) calculation (B3LYP/6-31G(d))).…”

“…double Friedel−Crafts reaction which we have recently developed 11. By oxidizing these cyclic π-conjugated molecules, we succeeded in synthesizing a dication with closed-shell singlet states instead of open-shell singlet states and a relatively stable monoradical cation (Figure…”