Copper-Catalyzed Regio- and Enantioselective Hydroallylation of 1-Trifluoromethylalkenes: Effect of Crown Ether
作者:Yuki Kojima、Masahiro Miura、Koji Hirano
DOI:10.1021/acscatal.1c02947
日期:2021.9.17
A Cu-catalyzedregio- and enantioselective hydroallylation of 1-trifluoromethylalkenes with hydrosilanes and allylic chlorides has been developed. An in situ generated CuH species undergoes the hydrocupration regio- and enantioselectively to form a chiral α-CF3 alkylcopper intermediate, which then leads to the optically active hydroallylated product. The key to success is the use of not only an appropriate
Remote Allylation of Unactivated C(sp<sup>3</sup>)–H Bonds Triggered by Photogenerated Amidyl Radicals
作者:Bin Xu、Uttam K. Tambar
DOI:10.1021/acscatal.9b00563
日期:2019.5.3
The allylationreaction is a highly versatile transformation in chemical synthesis. While many elegant direct C(sp2)–H allylationreactions have been developed, the direct allylation of unactivated C(sp3)–H bonds is underdeveloped. By applying photoredox catalysis and a [1,5]-HAT process, herein we report a direct allylation of unactivated C(sp3)–H bonds. This photocatalyzed transformation is tolerant
Ligand-Enabled Copper-Catalyzed Regio- and Stereoselective Allylboration of 1-Trifluoromethylalkenes
作者:Yuki Kojima、Yuji Nishii、Koji Hirano
DOI:10.1021/acs.orglett.2c03024
日期:2022.10.14
A copper-catalyzed regio- and stereoselectiveallylboration of 1-trifluoromethylalkenes with bis(pinacolato)diboron (pinB–Bpin) and allylic chlorides has been developed to form functionalized trifluoromethylated products with high diastereoselectivity. The key to success is the judicious choice of Cs2CO3 base and t-Bu-modified dppe-type ligand, which enables the otherwise challenging high catalyst
Synthesis of Poly(2-substituted-1-propenylene)s from Allylic Arsonium Ylides
作者:Régis Mondière、Jean-Philippe Goddard、Géraldine Carrot、Thierry Le Gall、Charles Mioskowski
DOI:10.1021/ma047693e
日期:2005.2.1
The polymerization of several allylic triphenylarsonium ylides, which contain a pendant R group at the 2-position, in the presence of triethylborane. is described. Three initial molar ratios of ylide to triethylborane (15, 302 60) were used, leading to different degrees of polymerization. The ylide was generated from the corresponding arsonium salt, in THF at -78 degreesC: using either tert-butyllithium (when R = alkyl) or lithium hexamethyldisilazide (when R = tBuMe(2)SiOCH(2)CH(2)(-)) as the haze. After addition of triethylborane at 0 degreesC, the deep-red solution of ylide was readily discolored. Then oxidation of the resulting polymeric borane led to linear skipped polyenes containing a terminal alcohol function. These polymers can be called poly(2-substituted-1-propenylene)s. Molecular weights have been determined from both H-1 NMR analyses and size exclusion chromatography (SEC). In most, cases, the molecular weight of the polymers increases linearly with the initial ylide/triethylborane molar ratio. which gives credit to a controlled polymerization process. Block copolymers were also obtained from triethylborane by, successive additions of two different 2-substituted allylic arsonium ylides, followed by oxidation (yield: 62-85%).