Cycloaddition of (phenylsulfonyl)-1,2-propadienes with diazomethane. Novel rearrangement reactions of the resulting cycloadducts
摘要:
The cycloaddition reactions of several phenylsulfonyl-substituted allenes with diazomethane have been investigated. The major products formed were identified as 3-(phenylsulfonyl)-4-methylene-2-pyrazolines. These pyrazolines engage in a variety of mechanistically interesting transformations, ranging from base-catalyzed rearrangements to addition of Grignard reagents. The dipolar cycloadduct derived from the reaction of diazomethane with 3-(phenylsulfonyl)-1,2-butadiene undergoes a 1,3-phenylsulfonyl shift upon irradiation to give 3-methyl-4-[(phenylsulfonyl)methyl]pyrazole. The cycloadduct derived from there action of 2,3-bis(phenylsulfonyl)-1-propene with diazomethane readily loses nitrogen upon photolysis to give 1-[(phenylsulfonyl)methyl]-1-(phenylsulfonyl)cyclopropane. This cyclopropane affords a variety of novel rearranged structures when treated with several different bases. The products obtained can be rationalized in terms of a base-catalyzed rearrangement of the above cyclopropane to a-methyl(phenylsulfonyl)allene which reacts further with the particular base used to produce the observed products.
Regiocontrolled Cu<sup>I</sup>-Catalyzed Borylation of Propargylic-Functionalized Internal Alkynes
作者:Abraham L. Moure、Ramón Gómez Arrayás、Diego J. Cárdenas、Inés Alonso、Juan C. Carretero
DOI:10.1021/ja300627s
日期:2012.5.2
orbitalic influence from the propargylic group, matched with ligand and substrate size effects, as key factors involved in the high β-selectivity. The vinylboronates allowed the stereoselective synthesis of trisubstituted olefins, while allylic substitution of the SO(2)Py group without affecting the boronate group provided access to formal hydroboration products of unbiased dialkylalkynes.
The [2,3]-sigmatropic rearrangement of propargyl benzenesulphinates to allenyl phenyl sulphones
作者:S. Braverman、H. Mechoulam
DOI:10.1016/s0040-4020(01)97078-4
日期:1974.1
undergo thermalrearrangement in high yields to sulphones, accompanied by a simultaneous acetylene-allene isomerization. The allenic sulphones produced by the rearrangement of the α-monosubstituted propargyl esters underwent further rearrangement under the reaction conditions, to γ-substituted propargyl phenyl sulphones, by way of a base-catalyzed [1,3] - prototropic shift. A kinetic study of the rearrangement
with several nucleophiles to give multi-substituted cyclobutanes. The reaction of the cyclobutylmagnesium carbenoids with lithium α-sulfonyl carbanions afforded alkylidenecyclobutanes in moderate to good yields. cyclobutane - alkylidenecyclobutane - magnesium carbenoid - cyclobutylmagnesium carbenoid - cyclobutylmagnesium chloride