Catalytic Enantioselective Dehydrogenative Si-O Coupling to Access Chiroptical Silicon-Stereogenic Siloxanes and Alkoxysilanes
A rhodium-catalyzed enantioselective construction of triorgano-substituted silicon-stereogenic siloxanes and alkoxysilanes is developed. This process undergoes a direct intermolecular dehydrogenative Si-O coupling between dihydrosilanes with silanols or alocohols, giving access to a variety of highly functionalized chiral siloxanes and alkoxysilanes in decent yields with excellent stereocontrol, that significantly expand the chemical space of the silicon-centered chiral molecules. Further utility of this process was illustrated by the construction of CPL-active (circularly polarized luminescence) silicon-stereogenic alkoxysilane small organic molecules. Optically pure bis-alkoxysilane containing two silicon-stereogenic centers and three pyrene groups displayed a remarkable glum value with a high fluorescence quantum efficiency (glum = 0.011, φF = 0.55), which could have great potential application prospects in chiral organic optoelectronic materials.
Zhu, Jiefeng,Chen, Shuyou,He, Chuan
supporting information
p. 5301 - 5307
(2021/05/04)
Asymmetric Synthesis of Silicon-Stereogenic Silanes by Copper-Catalyzed Desymmetrizing Protoboration of Vinylsilanes
The catalytic asymmetric creation of silanes with silicon stereocenters is a long-sought but underdeveloped topic, and only a handful of examples have been reported. Moreover, the construction of chiral silanes containing (more than) two stereocenters is a more arduous task and remains unexploited. We herein report an unprecedented copper-catalyzed desymmetrizing protoboration of divinyl-substituted silanes with bis(pinacolato)diboron (B2pin2). This method enables the facile preparation of an array of enantiomerically enriched boronate-substituted organosilanes bearing contiguous silicon and carbon stereocenters with exclusive regioselectivity and generally excellent diastereo- and enantioselectivity.
Stereo- And regio-selective synthesis of silicon-containing diborylalkenes: via platinum-catalyzed mono-lateral diboration of dialkynylsilanes
A highly chemoselective platinum-catalyzed mono-lateral diboration of dialkynylsilanes for the construction of silicon-tethered alkynyl diborylalkenes is described, in which tris(4-methoxyphenyl)phosphine was found to be an effective ligand for the cis-addition of diboron agents to the silicon-tethered alkynes, and the chiral ligand (AFSi-Phos)-mediated diboration of dialkynylsilanes resulted in the desymmetric construction of silicon-stereogenic centers with promising enantioselectivity.
1-t-Butyl-1-phenyl-1-silacyclohexane: Synthesis, conformational analysis in gas and solution by GED, FT-IR and theoretical calculations
1-t-Butyl-1-phenyl-1-silacyclohexane 1, the first disubstituted silacyclohexane with the most bulky substituent, t-Bu group, at silicon, was synthesized via the sequence of reactions PhSiCl3 → Ph(Cl)Si(CH2)5 → Ph(t-Bu)Si(C
Oznobikhina, Larisa P.,Phien, Tran Dinh,Shainyan, Bagrat A.,Shlykov, Sergey A.,Suslova, Elena N.
(2020/07/31)
Unpredictable reaction of phenyltrichlorosilane with tert-butyllithium
The reaction of PhSiCl3 with one equivalent of Li[tBu] at r. t. yielded tBuPhSiCl2 whereas tBu2PhSiCl was only a minor product of the reaction of two molar equivalents Li[tBu] with PhSiCl3 at 60 °C. By contrast,