intermediates have been widely applied in the synthesis of functionalized allenes, but reactions involving allenyl radicals have been less studied and limited successful examples have been realized mainly by transition metal catalysis. We herein demonstrate the generation of allenyl radicals by N-heterocycliccarbene (NHC) organocatalysis and their applications in the three-component radical relay 1,4-alkylcarbonylation
Switch in Selectivity for Formal Hydroalkylation of 1,3‐Dienes and Enynes with Simple Hydrazones
作者:Leiyang Lv、Lin Yu、Zihang Qiu、Chao‐Jun Li
DOI:10.1002/anie.201915875
日期:2020.4.16
anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes
Through the use of [PdCl(C3H5)]2/cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as catalyst, a range of vinylbromides undergoes Sonogashira cross-coupling reaction with a variety of alkynes, leading to the corresponding 1,3-enynes in good yields. The reaction tolerates several alkynes such as phenylacetylene, dec-1-yne, 2-methylbut-1-en-3-yne a range of alk-1-ynols, 3,3-diethoxyprop-1-yne
通过使用[PdCl(C 3 H 5)] 2 /顺式,顺式,顺式-1,2,3,4-四(二苯基膦甲基)环戊烷作为催化剂,一定范围的乙烯基溴与各种炔烃进行Sonogashira交叉偶联反应,从而以高收率得到相应的1,3-烯炔。该反应可耐受几种炔烃,例如苯乙炔,癸-1-炔,2-甲基丁-1-烯-3-炔,一系列烷-1-炔醇,3,3-二乙氧基丙-1-炔和炔丙基胺。在苯乙炔,dec-1-yne,but-3-yn-1-ol,pent-4-yn-1-ol,3,3-dithoxyprop-1-yne或1,1存在下观察到更高的反应速率-二丙基-2-丙炔胺比与炔丙醇,3-甲氧基-丙-1-炔或2-甲基丁-1-烯-3-炔。该催化剂即使在空间受阻的乙烯基溴化物如溴代三苯基乙烯或2-溴-3-甲基-丁-2-烯的反应中也可以低负荷使用。
Copper-Catalyzed Syntheses of Multiple Functionalizatized Allenes via Three-Component Reaction of Enynes
作者:Yulong Song、Chunling Fu、Shengming Ma
DOI:10.1021/acscatal.1c02140
日期:2021.8.6
oxime esters and 1,3-enynes in the presence of TMSCN or TMSCF3 has been developed. This mild protocol enjoys a broad substrate scope tolerating many functional groups, providing a facile access to 1,7-double-functionalized allenes, which are difficult to prepare. The allenyl nitrile products may be easily transformed into allenoic acid derivatives and stereodefined tetrasubstituted alkenes, demonstrating
Cobalt-Catalyzed Sequential Site- and Stereoselective Hydrosilylation of 1,3- and 1,4-Enynes
作者:Wenxin Lu、Yongmei Zhao、Fanke Meng
DOI:10.1021/jacs.2c00288
日期:2022.3.30
center. Reactions of 1,4-enynes proceeded through sequential isomerization of the alkene moiety followed by site- and stereoselective hydrosilylation. A wide range of alkenylsilanes were afforded in high efficiency and selectivity. Functionalization of the enantioenriched silanes containing a stereogenic center at silicon delivered a variety of chiral building blocks that are otherwise difficult to access