Synthesis of Functionalized Epoxides by Copper-Catalyzed Alkylative Epoxidation of Allylic Alcohols with Alkyl Nitriles
作者:Ala Bunescu、Qian Wang、Jieping Zhu
DOI:10.1021/acs.orglett.5b00571
日期:2015.4.17
A copper-catalyzed oxyalkylation of allylic alcohols using nonactivated alkyl nitriles as reaction partners was developed. A sequence involving generation of an alkyl nitrile radical followed by its addition to a double bond and a copper-mediated formation of C(sp3)–O bond was proposed to account for the reaction outcome. The protocol provided an efficient route to functionalized tri- and tetrasubstituted
Asymmetric Chlorination/Ring Expansion for the Synthesis of α-Quaternary Cycloalkanones
作者:Qin Yin、Shu-Li You
DOI:10.1021/ol5005565
日期:2014.3.21
A highly enantioselective chlorination/ringexpansion cascade for the construction of cycloalkanones with an all-carbon quaternary center was realized (up to 97% ee). Oxa-cyclobutanol substrates were employed for the first time in the ringexpansionreactions, affording the functionalized dihydrofuranones in excellent enantioselectivity.
A catalytic allylic cation-induced intermolecular allylation-semipinacol rearrangement
作者:Ming-Hui Xu、Kun-Long Dai、Yong-Qiang Tu、Xiao-Ming Zhang、Fu-Min Zhang、Shao-Hua Wang
DOI:10.1039/c8cc04285c
日期:——
A catalytic intermolecular semipinacol rearrangement induced by allylic carbocations has been realized. This tandem reaction is highly efficient under the catalysis of ZnBr2, generating a wide range of α-homoallyl substituted ketones which contain all-carbon quaternary centres in good to excellent yields (up to 98%) with moderate to high diastereoselectivities (up to >20 : 1). Synthetic application
sulfonylation/semipinacol rearrangements of allylic alcohols were developed using cheap and stable RSO2Na (R = CF3, Ph) as reagents. Various β-trifluoromethyl and sulfonated ketones were obtained in moderate to excellent yields. This strategy provides a facile, direct, and complementary approach to construct all-carbon quaternary stereocenters. In addition, the reaction has the advantages of being chemical oxidant-free
Visible‐Light Photoredox‐Catalyzed Semipinacol‐Type Rearrangement: Trifluoromethylation/Ring Expansion by a Radical–Polar Mechanism
作者:Basudev Sahoo、Jun‐Long Li、Frank Glorius
DOI:10.1002/anie.201503210
日期:2015.9.21
semipinacol‐type rearrangement proceeding via 1,2 alkyl migration was developed. In this transformation, trifluoromethylation of the CC bond of α‐(1‐hydroxycycloalkyl)‐substituted styrene derivatives is followed by ringexpansion of the 1‐hydroxycycloalkyl group to deliver novel cycloalkanones with all‐carbon quaternary centers. The reaction proceeds via a radical–polar mechanism, with trifluoromethylation