Clean and convenient procedure for converting primary alkyl iodides and .alpha.,.omega.-diiodoalkanes into the corresponding alkyllithium derivatives by treatment with tert-butyllithium
and proton sponge in toluene, terminalalkynes were found to undergo the alkylation by alkyl triflates to provide unsymmetrical internal alkynes. This is the first example that a simple alkyl chain other than benzylic and norbornyl units can be introduced onto the alkynyl carbon atom under Lewis acid catalysis. Mechanisticstudies revealed that the activation of the alkyne by the zinc Lewis acid and proton
C(carbene)N(amido)N(amine)-pincer nickel(II) complexes [iPrCNN-Ni-Br] (6), [nBuCNN-Ni-Br] (7) and [BnCNN-Ni-Cl] (8) were synthesized. The catalytic performance of complexes 6–8 for Sonogashira cross-coupling reactions was explored. In a combination of 5 mol% catalyst loading of 6 and CuI/Cs2CO3/NaI/DMSO at different temperatures for the coupling reactions between alkyl iodides, bromides, chlorides
C(卡宾)N(酰胺基)N(胺)-钳制镍(II)络合物[ iPr CNN-Ni-Br](6),[ n Bu CNN-Ni-Br](7)和[ Bn CNN-Ni-Ni-合成了Cl](8)。探索了配合物6-8对Sonogashira交叉偶联反应的催化性能。在5 mol%的催化剂中负载6和CuI / Cs 2 CO 3/ NaI / DMSO在不同温度下用于烷基碘化物,溴化物,氯化物和末端炔烃之间的偶联反应,可以中等至极好的收率获得相应的偶联产物。讨论了这些催化反应的机理,并得到了实验的部分支持。分离出作为催化活性络合物的苯基乙炔基CNN钳形镍络合物9,并使用X射线衍射对其结构进行了表征。
Synthesis of five-membered unsaturated compounds from ketones via cyanophosphates under neutral conditions: [1,5]-C H insertion of alkylidene carbenes generated by tetrazole fragmentation
Cyanophosphates (CPs) can easily be prepared via the reactions of carbonyl compounds with diethyl phosphorocyanidate (DEPC) in the presence of LiCN (cat.) under non-aqueous conditions. Treatment of ketone-derived CPs with TMSN3/Bu2SnO (cat.) in toluene at reflux produces cyclopentenes or heterocyclic products in good yields under neutral conditions. In this two-step transformation, CPs may form tetrazolylphosphates
在非水条件下,在LiCN(cat。)存在下,羰基化合物与磷腈二乙酯(DEPC)的反应可轻松制得氰基磷酸盐(CPs)。在中性条件下,用甲苯中的TMSN 3 / Bu 2 SnO(cat。)在甲苯中处理酮衍生的CP,可以高产率生产环戊烯或杂环产物。在此两步转化过程中,CP可能形成四唑基磷酸酯,随后对其进行连续裂解以生成亚烷基卡宾,这些卡宾经过[1,5] -CH插入可生成五元化合物。
Stereoselective cyclic carbolithiation of alkyne derivatives. A stereoselective synthesis of exocyclic alkenes
作者:Guangzhong Wu、Fredrick E Cederbaum、Ei-ichi Negishi
DOI:10.1016/0040-4039(90)87016-s
日期:1990.1
(Trimethylsilyl)alkyne derivatives that are lithiated in the δ position via non-radical routes can cyclize in a stereoselective manner (≥96-98%) to give exocyclic alkenes containing five-membered carbocycles in high yields.
Exploiting the inductive effect of the trifluoromethyl group: regioselective gold-catalyzed hydration of 2,2,2-trifluoroethyl-substituted alkynes
作者:Raphaël Gauthier、Nikolaos V. Tzouras、Steven P. Nolan、Jean-François Paquin
DOI:10.1039/d3cc02034g
日期:——
2-trifluoroethyl-substituted alkynes is highly regioselective, producing β-trifluoromethylketones as major products. This transformation illustrates the strong directing effect of the trifluoromethylgroup, through its inductive effect, in gold-catalyzed addition to alkynes.