Synthesis of Silylboronic Esters Functionalized on Silicon
摘要:
New silylpinacolboranes bearing chloro, fluoro, alkoxy, and dialkylamino groups on silicon were synthesized in high yields via derivatization of [(diethylamino)diphenylsilyl]pinacolborane, which was prepared by reaction of [(diethylamino)diphenylsilyl]lithium with (isopropoxy)pinacolborane, and (chlorodimethylsilyl)pinacolborane, prepared by reaction of (dimethylphenylsilyl)pinacolborane with hydrogen chloride in the presence of a catalytic amount of aluminum chloride.
2 + 1] cycloaddition takes place in the rhodium-catalyzed reaction of 1,6-enynes with borylsilanes bearing an alkoxy group on the silicon atoms, which react as synthetic equivalents of silylene. The reaction proceeds efficiently in 1,2-dichloroethane at 80–110 °C in the presence of a rhodium catalyst bearing bis(diphenylphosphino)methane (DPPM) as a ligand to afford 1-silacyclopent-2-enes in good to
involving 1,3-diene, alkyne, and silylene to afford silicon-containing seven-memberedrings was established. In the presence of a rhodium catalyst bearing bis(diphenylphosphino)methane (DPPM), nona-1,3-dien-8-yne derivatives reacted efficiently at 80–110 °C with boryl(isopropoxy)silane or boryl(diethyamino)silane, which reacts as the synthetic equivalent of silylene, to afford 1-silacyclohepta-2,5-dienes (2
建立了铑催化的[4 + 2 + 1]环加成反应,该反应涉及1,3-二烯,炔烃和亚甲硅烷基,以提供含硅的七元环。在带有双(二苯基膦基)甲烷(DPPM)的铑催化剂的存在下,壬基1,3-三烯-8-炔衍生物在80–110°C下与硼基(异丙氧基)硅烷或硼基(二乙氨基)硅烷有效反应,其作为亚甲硅烷基的合成当量反应,得到1-silacyclohepta-2,5-二烯(2,5-二氢-1 H-西勒平)。七元非共轭二烯的区域发散性和化学和立体选择性官能化是通过Cs 2 CO 3或铱催化剂介导的硼氢化作用实现的。
Synthesis of Disilanes, Dihydrosiloles, and 1,4‐Disilacyclohexa‐2,5‐dienes by Transition‐Metal‐Free Transfer of Diphenylsilylene and Dimethylsilylene from Silylboronic Esters
Transfer of diphenylsilylene (Ph2Si:) and dimethylsilylene (Me2Si:) from silylboronic esters takes place at 110–135 °C under transition-metal-free conditions. The reaction with alkoxysilanes, 1,3-dienes, and an alkyne affords alkoxydisilanes, dihydrosiloles, and 1,4-disilacyclohexa-2,5-dienes, respectively, in good to high yields.
Silylpinacolboranes bearing dialkylamino groups on the silicon atom several as synthetic equivalents of silylene in palladium-catalyzed reactions with terminal alkynes, leading to the formation of 2, 4-disubstituted siloles in high yield. It was found that the amino group on the silicon atom was critically important for the reaction; no silole products were found in reactions using silylpinacolboranes carrying aryl, chloro, or alkoxy groups on the silicon atoms. Site-selective bromination of 1,1-dimethyl-2,4-diphenylsilole followed by Migita-Kasugi-Stille coupling with (arylalkynyl)tributylstannanes gave novel Pi-conjugated siloles with good total yields.
2-Vinylindoles As the Four-Atom Component in a Catalytic [4+1] Cycloaddition with a Silylene-Palladium Species Generated from (Aminosilyl)boronic Ester
The palladium-catalyzed silylene transfer to 2-alkenylindoles from a silylboronic ester bearing a diethylamino group on the silicon atom takes place efficiently, resulting in the formation of a 1-sila-3-cyclopentene ring fused with the indole ring. Further silylene transfer proceeds in the reaction of 2-(1-alkenyl)indoles, giving bissilylated tricyclic indoles in high yields.