Synthesis, Structure and Reactivity of some 2,6‐Disubstituted Dimethylsilylbenzenes

Abstract

Syntheses are described of a number of 2,6-difunctionalized dimethylsilylbenzenes, namely1233 benzo[d][2,1,3]ferra disilol (20). Compounds 13Ϫ20 were characterized by multinuclear NMR spectroscopy and in case of 18Ϫ20 also by single crystal X-ray diffraction.

Reactivity of 2,6‐Dihalophenyl Lithium Reagents Towards Chlorosilanes. Synthesis and Structure of 2,3‐ and 2,6‐Dihalophenyl(di‐)silanes

“…The 29 Si NMR chemical shift of [(2,6‐F 2 C 6 H 4 )Me 2 Si] 2 ( 1a , δ = –21.7 ppm) is identical with that of the parent compound (PhMe 2 Si) 2 ( δ = –21.7 ppm), whereas those of [(2,6‐Cl 2 C 6 H 4 )Me 2 Si] 2 ( 1b , δ = –11.5 ppm) and [(2,6‐Br 2 C 6 H 4 )Me 2 Si] 2 ( 1c , δ = –6.6 ppm) are shifted towards higher frequencies. A similar trend can also be observed for the aryldimethylsilanes PhSiMe 2 H ( δ = –18.1 ppm), 2,6‐F 2 C 6 H 4 SiMe 2 H ( δ = –21.7 ppm), 2,6‐Cl 2 C 6 H 4 SiMe 2 H ( δ = –15.8 ppm), and 2,6‐Br 2 C 6 H 4 SiMe 2 H ( δ = –15.4 ppm), however, the effect of the halogen atoms on the 29 Si NMR chemical shift is not as pronounced as in the series of the diaryltetramethyldilanes.…”

Silyl Cations Stabilized by Pincer Type Ligands with Adjustable Donor Atoms

“…[ 26 ] 2,6‐Dibromodimethylsilylbenzene, 2,6‐Br 2 C 6 H 3 SiMe 2 H ( 1b ), was obtained similarly as already described. [ 27 ] The preparation of 2,6‐bis(diphenylphosphino)dimethylsilylbenzene, 2,6‐(Ph 2 P) 2 C 6 H 3 SiMe 2 H ( 2 ), was achieved in two complementary ways, namely, the reaction of 1a with two equivalents of Ph 2 PLi and the double lithiation of 1b with n BuLi/TMEDA prior to the reaction with two equivalents of Ph 2 PCl, respectively (Scheme 3). The former reaction entails a nucleophilic substitution at the aromatic ring, while the latter involves a nucleophilic substitution at the P atom.…”

How to Make the Ionic Si−O Bond More Covalent and the Si−O−Si Linkage a Better Acceptor for Hydrogen Bonding

“…Synthesis of 5-Dimethylhydroxysilyl-1,3-dihydro-1,1,3,3-tetramethyl-2,1,3-benzoxadisilole (1). A solution of 1,2,3-tris(dimethylsilyl)benzene 36 (1.00 g, 3.95 mmol) in THF (20 mL) was slowly added to a suspension of Pearlman's catalyst C/Pd(OH) 2 (25 mg) in THF (90 mL) and water (10 mL). After the evolution of hydrogen gas had ceased (approximately 2 h), the catalyst was filtered off, and the solvent evaporated under reduced pressure.…”