Nickel-catalyzed, highly diastereoselective annulations between activated allenes and 2-acetylarylboronic acid or 2-formylarylboronic acids are reported. No ligand for nickel is required, and the reactions proceed efficiently at room temperature to give a broad range of substituted 3-methyleneindan-1-ols. Preliminary results of an enantioselective variant are also described.
Formal (4 + 1)-Addition of Allenoates to <i>o</i>-Quinone Methides
作者:Katharina Zielke、Mario Waser
DOI:10.1021/acs.orglett.7b03906
日期:2018.2.2
The first (4 + 1)-annulation of o-quinonemethides with α-branched allenoates as C1 synthons has been developed. This operationally simple protocol gives access to highly functionalized dihydrobenzofurans in an unprecedented fashion with excellent diastereoselectivities and high yields.
Phosphine-Mediated Stereoselective Reductive Cyclopropanation of α-Substituted Allenoates with Aromatic Aldehydes
作者:Silong Xu、Lili Zhou、Renqin Ma、Haibin Song、Zhengjie He
DOI:10.1021/ol902747c
日期:2010.2.5
cyclopropanation between α-substituted allenoates2 and aldehydes 1 is described. It represents a new member of the allene-based annulations, which provides facile and efficient access to highly functionalized cyclopropanes 3 from simple and readily available starting materials. It also unveils an unprecedented reactivity pattern of allenoates with aldehydes.
Multicomponent Cascade Cycloaddition Involving Tropone, Allenoate, and Isocyanide: A Rapid Access to a 7,6,5-Fused Tricyclic Skeleton
作者:Shuanglong Jia、Shikuan Su、Chunju Li、Xueshun Jia、Jian Li
DOI:10.1021/ol502656g
日期:2014.11.7
Multicomponent cascade cycloaddition of tropone, allenoate, and isocyanide has been disclosed. This method allows for the rapid construction of a highly unusual tricyclic skeleton in an efficient manner. The proposed transformation proceeds through [8 + 2 + 1] cycloaddition, [1,5]-H shift, and cyclization followed by an alkoxy group migration process.
Stereoselective Synthesis of 1,2,3,4-Tetrasubstituted Dienes from Allenoates and Aldehydes: An Observation of Phosphine-Induced Chemoselectivity
作者:Silong Xu、Wen Zou、Guiping Wu、Haibin Song、Zhengjie He
DOI:10.1021/ol101429z
日期:2010.8.6
Phosphine-mediated olefination between a-substituted allenoates and aldehydes to form 1,2,3,4-tetrasubstituted 1,3-dienes is presented. High levels of chemo- and diastereoselectivity and yield are obtained for a wide scope of substrates with the choice of appropriate phosphines. This reaction evidences the capacity of phosphines in the control of reaction pathways and provides a highly efficient synthetic method for tetrasubstituted conjugated dienes.