We describe a convenient method for the synthesis of multisubstituted allenesfrom cross-coupling of propargylacetates with organoaluminum reagent: The reaction of propargylacetates with 1.2 equivalents of organoaluminum reagentmediated by Pd(PPh 3 ) 2 Cl 2 (1 mol%)/Ph 3 P (2 mol%) and K 2 CO 3 in THF may produce tri- or tetrasubstituted allenes in good to excellent yields (83–94%) and high regioselectivities
我们描述了一种通过乙酸炔丙酯与有机铝试剂的交叉偶联合成多取代丙二烯的简便方法:乙酸炔丙酯与 1.2 当量有机铝试剂的反应由 Pd(PPh 3 ) 2 Cl 2 (1 mol%)/Ph 介导THF 中的 3 P (2 mol%) 和 K 2 CO 3 可以在 60 °C 下在 3-4 小时内以良好到优异的产率 (83–94%) 和高区域选择性(高达 99%)生成三或四取代的丙二烯.
Synthesis of multi-substituted allenes from organoalane reagents and propargyl esters by using a nickel catalyst
作者:Xue Bei Shao、Zhen Zhang、Qing Han Li、Zhi Gang Zhao
DOI:10.1039/c8ob00781k
日期:——
A highly efficient and simple route for the synthesis of multi-substituted allenes has been developed by a nickel catalyzed SN2′ substitution reaction of propargyl esters with organic aluminium reagents under mild conditions, which gave the corresponding multi-substituted allenes in good to excellent yields (up to 92%) and high selectivities (up to 99%) at 60 °C for 6 h in THF. Aryls bearing electron-donating
在温和的条件下,通过炔丙基酯与有机铝试剂的镍催化的S N 2'取代反应,开发了一种高效且简单的合成多取代的烯的方法,得到了相应的优等的多取代的烯。在THF中在60°C下反应6小时可得到高产率(最高92%)和高选择性(最高99%)。炔丙基酯中带有给电子或吸电子基团的芳基收率高。另外,带有噻吩基或吡啶基的多取代的亚丙基以95-97%的选择性获得,分离产率为72-83%。此外,S N2'取代反应也与炔丙基碳酸酯化合物有效地起作用。根据实验结果,提出了可能的催化循环。
Stereospecific Synthesis of Allenes from β‐Ketosulfones
Enolates formed from 1-phenyl-5-tetrazolyl β-ketosulfones containing a tetrasubstituted α carbon centre undergo elimination to allenes with up to four substituents at the cumulene unit when treated with a weak base (phenolate) in DMSO at room temperature. The reaction is completely regioselective for allene vs diene formation in nearly all investigated cases and it proceeds with central-to-axial chirality