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 hydroxycyclopenten-1-ones
申请人:Hoffmann-La Roche Inc.
公开号:US03978093A1
公开(公告)日:1976-08-31
This invention relates to a process for the preparation of 2-alkenyl-4-hydroxy-3-methyl-2-cyclopenten-1-ones from the reaction product of 2,4-pentane dione and a 2-propen-or 2-propyn-1-ol derivative including intermediates therein.
This invention relates to a process for the preparation of 2-alkenyl-4-hydroxy-3-methyl-2-cyclopenten-1-ones from the reaction product of 2,4-pentane dione and a 2-propen-or 2-propyn-1-ol derivative including intermediates therein.
Controllable Access to Furans and Dihydrofurans through Cyclization/Coupling of Internal Acetylenic β‐Ketoesters with Aryl Bromides
作者:Bartosz Bisek、Wojciech Chaładaj
DOI:10.1002/adsc.202200686
日期:2022.12.20
Pd-catalyzed tandem cyclization/coupling of internal β-propargylic-β-ketoesters with (hetero)aryl bromides is described. Two protocols are established which selectively lead to 2-benzylidene-dihydrofurans, when isomerization is inhibited under mild conditions (temp. ≤40 °C and weak base – K2CO3), or to 2-benzyl-furans when base-induced aromatization is enabled. A catalytic cycle involving oxidative
描述了 Pd 催化的内部 β-炔丙基-β-酮酯与(杂)芳基溴化物的串联环化/偶联。建立了两种方案,当异构化在温和条件下(温度≤40 °C 和弱碱 – K 2 CO 3)被抑制时,选择性地产生 2-亚苄基-二氢呋喃,或在碱诱导芳构化时产生 2-苄基-呋喃已启用。基于详细的实验和理论研究,提出了涉及氧化加成、用炔取代溴化物、限速反选择性5-exo-dig氧环化随后氧鎓中间体快速去质子化和还原消除的催化循环。