A Novel platinum tetrachloride-catalyzed cyclorearrangement of allyl propynyl ethers to 3-oxabicyclo[4.1.0]heptenes.
摘要:
Allyl propynyl ethers of general formula RC-CCH2OCH2CH=CHR' (1) undergo cyclorearrangement to 3-oxabicyclo[4.1.0]hept-4-enes (2) in oxygen-free benzene upon brief treatment at room temperature with catalytic amount of PtCl4. The transformation of 1 to 2 is assumed to involve platinum-allene intermediates. The structure of 7-(1-naphthyl)-6-phenyl-3-oxabicyclo[4.1.0]hept-4-ene (2c) has been determined by X-ray diffraction analysis. The-naphthyl and phenyl groups were shown to be oriented cis to each other. In the presence of [(CO2)Rh(mu-Cl)](2) the oxabicycloheptenes 2 undergo cyclopropane-ring cleavage. 6,7-Diphenyl-3-oxabicyclo[4.1.0lhept-4-ene (2b) forms the rhodocyclic complex 3b. In the absence of air, the oxygen-free analog of 1a, PhC=C(CH2)(3)CH=CH2 (4), rearranges to the unstable 7-phenylbicyclo[3.2.0]hept-1(7)-ene (5), which can be trapped by oxygen as stable 2-(2-oxo-2-phenylethyl)cyclopentanone (6).
Bicyclization of Enynes Using the Cp2TiCl2−Mg−BTC System: A Practical Method to Bicyclic Cyclopentenones
摘要:
Bicyclic titanacycles 2 generated with the Cp2TiCl2-Mg-P(OEt)(3) system can be trapped with bis(trichloromethyl) carbonate (BTC) to give bicyclic cyclopentenones 3 in good yields. The titanacycle 2m was isolated and well-identified. Bicyclization of enynes containing 1,2-disubstituted olefin by this method gave good results with excellent stereoselectivity.
Gold(I)-Catalyzed Intermolecular Addition of Carbon Nucleophiles to 1,5- and 1,6-Enynes
作者:Catelijne H. M. Amijs、Verónica López-Carrillo、Mihai Raducan、Patricia Pérez-Galán、Catalina Ferrer、Antonio M. Echavarren
DOI:10.1021/jo8014769
日期:2008.10.3
Gold(I)-catalyzed addition of carbon nucleophiles to 1,6-enynes gives two different type of products by reaction at the cyclopropane or at the carbene carbons of the intermediate cyclopropyl gold carbenes. The 5-exo-dig cyclization is followed by most 1,6-enynes, although those bearing internal alkynes and alkenes react by the 6-endo-dig pathway. The cyclopropane versus carbene site-selectivity can
Trapping bicyclic titanacyclopentenes with bis(trichloromethyl) carbonate (BTC): a new method to bicyclic cyclopentenones
作者:Zongbao Zhao、Yu Ding
DOI:10.1039/a708182k
日期:——
Bis(trichloromethyl) carbonate is found to trap bicyclic titanacyclopentenes providing a new method for bicyclization of enynes into bicycliccyclopentenones.
发现碳酸二(三氯甲基)酯可捕获双环钛环戊烯,这为将烯炔双环化为双环环戊烯酮提供了一种新方法。
A Novel platinum tetrachloride-catalyzed cyclorearrangement of allyl propynyl ethers to 3-oxabicyclo[4.1.0]heptenes.
作者:Jochanan Blum、Hanita Beer-Kraft、Yacoub Badrieh
DOI:10.1021/jo00122a043
日期:1995.9
Allyl propynyl ethers of general formula RC-CCH2OCH2CH=CHR' (1) undergo cyclorearrangement to 3-oxabicyclo[4.1.0]hept-4-enes (2) in oxygen-free benzene upon brief treatment at room temperature with catalytic amount of PtCl4. The transformation of 1 to 2 is assumed to involve platinum-allene intermediates. The structure of 7-(1-naphthyl)-6-phenyl-3-oxabicyclo[4.1.0]hept-4-ene (2c) has been determined by X-ray diffraction analysis. The-naphthyl and phenyl groups were shown to be oriented cis to each other. In the presence of [(CO2)Rh(mu-Cl)](2) the oxabicycloheptenes 2 undergo cyclopropane-ring cleavage. 6,7-Diphenyl-3-oxabicyclo[4.1.0lhept-4-ene (2b) forms the rhodocyclic complex 3b. In the absence of air, the oxygen-free analog of 1a, PhC=C(CH2)(3)CH=CH2 (4), rearranges to the unstable 7-phenylbicyclo[3.2.0]hept-1(7)-ene (5), which can be trapped by oxygen as stable 2-(2-oxo-2-phenylethyl)cyclopentanone (6).
Bicyclization of Enynes Using the Cp<sub>2</sub>TiCl<sub>2</sub>−Mg−BTC System: A Practical Method to Bicyclic Cyclopentenones
作者:Zongbao Zhao、Yu Ding、Gang Zhao
DOI:10.1021/jo9810718
日期:1998.12.1
Bicyclic titanacycles 2 generated with the Cp2TiCl2-Mg-P(OEt)(3) system can be trapped with bis(trichloromethyl) carbonate (BTC) to give bicyclic cyclopentenones 3 in good yields. The titanacycle 2m was isolated and well-identified. Bicyclization of enynes containing 1,2-disubstituted olefin by this method gave good results with excellent stereoselectivity.