Steric Effects Compete with Aryne Distortion To Control Regioselectivities of Nucleophilic Additions to 3-Silylarynes
摘要:
We report an experimental and computational study of 3-silylarynes. The addition of nucleophiles yield ortho-substituted products as a result of aryne distortion, but meta-substituted products form predominately when the nucleophile is large. Computations correctly predict the preferred site of attack observed in both nucleophilic addition and cycloaddition experiments. Nucleophilic additions to 3-tert-butylbenzyne, which is not significantly distorted, give meta-substituted products.
Benzyne 1,2,4-Trisubstitution and Dearomative 1,2,4-Trifunctionalization
作者:Jiarong Shi、Lianggui Li、Chunhui Shan、Zhonghong Chen、Liang Dai、Min Tan、Yu Lan、Yang Li
DOI:10.1021/jacs.1c04389
日期:2021.7.21
4-trifunctionalization of benzyne have been accomplished from sulfoxides bearing a penta-2,4-dien-1-yl moiety. These cascade transformations proceed through a benzyne insertion into the S═O bond and an uncommon regiospecific anionic [4,5]-sigmatropic rearrangement, furnishing a C–O, C–S, and C–C bond on the C1-, C2-, and C4-position of a benzene ring, respectively. This study showcases new cascade benzyne reaction
of in situ generated arynes with vinyl sulfides provides benzannulated sulfonium ylides in a (3+2) cycloaddition. Trapping of the intermediate ylides with electrophiles (proton transfer or a second aryne addition) and subsequent β‐elimination give rise to di‐, tri‐, or tetrasubstituted alkenes with high stereoselectivity. Experimental studies and DFT calculations provide insight into the mechanisms of
2-difunctionalized benzenes, the sites other than its formal triple bond remain silent in typical benzyne transformations. An unprecedented aryne 1,2,3,5-tetrasubstitution was realized from 3-silylbenzyne and aryl allyl sulfoxide, the mechanistic pathway of which includes a regioselective aryne insertion into the S═O bond, a [3,6]-sigmatropic rearrangement, and a thermal aromatic 1,3-silyl migration cascade.
Reaction of Arynes with Vinyl Sulfoxides: Highly Stereospecific Synthesis of <i>ortho</i>-Sulfinylaryl Vinyl Ethers
作者:Yuanming Li、Armido Studer
DOI:10.1021/acs.orglett.6b03827
日期:2017.2.3
The reaction of in situ generated arynes with aryl vinyl sulfoxides provides ortho-arylsulfinylaryl vinylethers via aryne σ-bond insertion into the S–O-bond and concomitant stereospecific S–O-vinyl migration. The cascade allows preparing di- or trisubstituted vinylethers with excellent stereospecificity. The reactions proceed under mild conditions, the substrate scope is broad, and the products obtained