1,x-Elimination Reactions: Extending the Limits of a Classical Organic Reaction
作者:Christian Werner、Henning Hopf、Ina Dix、Peter Bubenitschek、Peter G. Jones
DOI:10.1002/chem.200700827
日期:2007.11.26
derivatives in which the two terminal carbon atom are separated by an unsaturated spacer unit ("pi spacer") undergo 1,x-elimination reactions (with x=6, 8, 10, and 14), using Mori's reagent (nBu3SnSiMe3/CsF). The resulting cumulenic intermediates cyclodimerize in a subsequent step yielding novel macrocyclic acetylenic and bridged aromaticcompounds (cyclophanes). Thus 1,6-eliminations were carried out with dibromide
使用森试剂,其中两个末端碳原子被不饱和间隔单元(“ pi spacer”)隔开的α,ω-二溴衍生物经历1,x消除反应(x = 6、8、10和14) (nBu3SnSiMe3 / CsF)。所得的异丙苯中间体在随后的步骤中环二聚,产生新的大环炔属和桥连的芳族化合物(环烷)。因此,用二溴化物17进行1,6-消除反应得到1,3,7,9-环十二碳酸酯(20),用苄基溴化物24进行环素26和27。通过1,8消除,16元大环化合物33可以由二烯化物31制备,苯甲酰化的1,5-环辛二炔41由二溴化物38制备,环烷酮45和46的混合物由前体43制备。成功地用二溴化物47,50进行1,10-消除,;和53产生相应的不饱和环烷(环戊烯)49、52和55。研究了溶剂对环二聚化47-> 49的影响,其中乙腈提供最高的收率。通过1,10消除前体二溴化物57a和b来获得杂物59a和b,在涉及二溴化物50和57b 1:
Gold- or Palladium-Catalyzed Allene Carbocyclization/Functionalization: Simple and Efficient Synthesis of Carbazoles
作者:Benito Alcaide、Pedro Almendros、José M. Alonso、M. Teresa Quirós、Paweł Gadziński
DOI:10.1002/adsc.201100209
日期:2011.8
Gold- and palladium-catalyzed cyclization of easily accessible indole-tethered allenols allows the efficient synthesis of carbazole derivatives under mild conditions.
金和钯催化环化的吲哚链烯醇容易获得,可在温和条件下有效合成咔唑衍生物。
Unveiling the uncatalyzed reaction of alkynes with 1,2-dipoles for the room temperature synthesis of cyclobutenes
2-(Pyridinium-1-yl)-1,1-bis(triflyl)ethanides have been used as 1,2-dipole precursors in a metal-free direct [2+2] cycloaddition reaction of alkynes. Remarkably, this mild and facile uncatalyzed protocol requires neither irradiation nor heating.
HCl or AcCl, at the central carbon of the mu-eta(3)-allenyl/propargyl ligand to give the mu-eta(3)-vinylcarbenedipalladium complexes. Intramolecular reaction proceeded smoothly to give cyclization products quantitatively. Addition of a catalytic amount of a palladium(0) complex dramatically accelerated the carbon-carbonbondformation. The MO calculations on the mu-eta(3)-allenyl/propargyl complexes indicated