Ruthenium-Catalyzed Cycloisomerization−6π-Cyclization: A Novel Route to Pyridines
摘要:
Herein we report a method for the synthesis of substituted pyridines. The unsaturated ketones and aldehydes derived from the cycloisomerization of primary and secondary propargyl diynols in the presence of [CpRu(CH3CN)(3)]PF6 (1) are converted to 1-azatrienes which in turn undergo a subsequent electrocyclization-dehydration to provide pyridines with excellent regiocontrol.
Palladium-catalyzed [3C + 2C + 2C] cycloaddition of enynylidenecyclopropanes: efficient construction of fused 5-7-5 tricyclic systems
作者:Gaurav Bhargava、Beatriz Trillo、Marisel Araya、Fernando López、Luis Castedo、José L. Mascareñas
DOI:10.1039/b919258a
日期:——
We report a Pd-catalyzed intramolecular [3C + 2C + 2C] cycloaddition between alkylidenecyclopropanes, alkynes and alkenes. The method provides synthetically relevant 5-7-5 tricyclic structures, with good chemoselectivity and complete diastereoselectivity.
Synthesis of Group 9 Metal-Olefin Complexes with Identical Ligand Frameworks and Comparison of their Catalytic Activity in [2+2+2] Cycloaddition and other Addition Reactions
The preparation and catalytic evaluation of the three group 9 (cyclopentadienyl)metal(trimethylvinylsilane) complexes of the type C5H5M(H2CCHSiMe3)2 (M=cobalt, rhodium and iridium) are reported. The complexes were investigated in [2+2+2] cycloaddition as well as in hydrogenation, hydroformylation and hydroboration reactions. Despite the identical organic frameworks and structural parameters, the complexes
One-step formation of fused tetracyclic skeletons from cyclohexene-diynes and carbon monoxide through Rh(i)-catalyzed [2 + 2 + 2 + 1] cycloaddition reaction
作者:Joseph J. Kaloko、Yu-Han Gary Teng、Iwao Ojima
DOI:10.1039/b909781c
日期:——
Rapid construction of 5-7-6-5 fused tetracyclic carbocycles and heterocycles from cyclohexene-diynes and CO has been achieved in one step through a Rh(i)-catalyzed [2 + 2 + 2 + 1] cycloaddition process.
Thermal [2+2] Cycloaddition of Allenynes: Easy Construction of Bicyclo[6.2.0]deca-1,8-dienes, Bicyclo[5.2.0]nona-1,7-dienes, and Bicyclo[4.2.0]octa-1,6-dienes
the allenyl group, in xylene (or mesitylene) without microwave irradiation resulted in the efficient formation of bicyclo[5.2.0]nona-1,7-dienes and bicyclo[4.2.0]octa-1,6-dienes in high yields. This method was shown to be successfully applicable to the first construction of bicyclo[6.2.0]deca-1,8-dienes. Construction of the corresponding oxa- and azabicyclo[m.2.0] frameworks could also be attained.
Disclosed is a process for production of a substituted benzene, which comprises intramolecularly and/or intermolecularly trimerizing a triple bond in an alkyne in the presence of a transition metal catalyst to yield a substituted benzene compound. In the process, the transition metal catalyst is prepared from an iminomethylpyridine represented by the formula (1) or (2), a transition metal salt or a hydrate thereof, and a reducing agent in a reaction system and is used to perform the trimerization. The process can be used in any one of the intramolecular cyclization of a triyne compound, the cyclization of a diyne compound or an alkyne compound and the intermolecular cyclization of three molecules of an alkyne compound, is excellent in economic effectiveness and operability, and is practically advantageous.
wherein R
1
and R
3
independently represent a linear or cyclic C
1
-C
20
aliphatic hydrocarbon group or the like; R
2
represents a hydrogen atom or the like; X represents a hydrogen atom, O or the like; and Y represents O, S or the like.