Metal-Catalyzed Chemoselective Cycloisomerization of cis-2,4-Dien-1-als to 3-Cyclopentenones and 4-Alkylidene-3,4-dihydro-2H-pyrans
摘要:
[GRAPHICS]PtCl2 (5 mol %) catalyst effected cycloisomerization of cis-2,4-dien-1-al (1) to 3-cyclopentenone (3) efficiently in hot toluene. In the presence of p-TSA, this PtCl2 catalysis gave 2-cyclopentenone (5) exclusively because of the secondary isomerization reaction. Although the 1-2 equilibrium state greatly favors aldehyde (1), PdCl2(PhCN)(2)(5 mol %) catalyzed cycloisomerization of aldehyde (1) to 4,6,7,8-tetrahydro-3H-isochromene (4) smoothly in hot toluene. A plausible mechanism is proposed on the basis of reaction observation and isotope-labeled experiment.
Valenzisomerisierung voncis-Dienonen I. 2-Vinyl-3,4,5,6-tetrahydrobenzaldehyd; Pyrolyse. von 6-Oxabicyclo [3,1,0] hex-2-en [1]
作者:P. Schiess、H. L. Chia
DOI:10.1002/hlca.19700530305
日期:——
The synthesis of 2-vinyl-3,4,5,6-tetrahydrobenzaldehyde (10) is described. This compound equilibrates above 70° with its valence isomer 4,5-tetramethylene-2H-pyran (11) as can be shown by cis-trans-isomerization of the double bond in selectively deuterated 10. The unstable 2H-pyran 11 can be trapped as tetracyanoethylene adduct 12.
Gold-Catalyzed Deoxygenated Cyclization of <i>cis</i>-2,4-Dien-1-als with Regioselective Addition of Two Nucleophiles. One-Pot Synthesis of Highly Functionalized Cyclopentene Framework
作者:Chung-Chang Lin、Tse-Min Teng、Arjan Odedra、Rai-Shung Liu
DOI:10.1021/ja069171f
日期:2007.4.1
We report a new gold-catalyzed deoxygenated cyclization of cis-2,4-dien-1-als with external nucleophiles at ambient temperatures, which leads to a 1,4-double nucleophilic addition to the newly formed cyclopentene ring. The use of this cyclization is reflected not only by its compatibility with a wide scope of nucleophiles, but also by a facile construction of complex frameworks in diversified approaches
Gold-Catalyzed Deoxygenative Nazarov Cyclization of 2,4-Dien-1-als for Stereoselective Synthesis of Highly Substituted Cyclopentenes
作者:Chung-Chang Lin、Tse-Min Teng、Chung-Chih Tsai、Hsin-Yi Liao、Rai-Shung Liu
DOI:10.1021/ja806415t
日期:2008.12.3
annulation products reveals evidence for the participation of Nazarov cyclization. This deoxygenative cyclization is extensible to a tandemintramolecularcyclization/nucleophilic addition cascade, giving polycyclic carbo- or oxacyclic compounds with controlled stereochemistry. This new gold catalysis is applied to a short synthesis of natural compounds of the brazilane family, including brazilane, O-trimethyl-
A study of periselectivity in the thermal cyclisation reactions of diene-conjugated diazo compounds: 1,7-cyclisation as a route to 3H-1,2-diazepines and 1,5-cyclisation leading to new rearrangement reactions of 3H-pyrazoles
作者:Ian R. Robertson、John T. Sharp
DOI:10.1016/s0040-4020(01)82434-0
日期:1984.1
A range of diene-conjugated diazo compounds has been generated by the thermal decomposition of the sodium salts of the tosylhydrazones of 1-acyl-1, 3-dienes. Those of type (21) with a relationship of the diazo group and the γ, δ-double bond having a hydrogen atom at the diene terminus cyclised only by 1,7 ring closure to give 3-1,2-diazepines (23). This mode of cyclisation was inhibited by the presence