过渡金属催化的炔丙基亲电子试剂和格氏试剂的交叉偶联提供了高度官能化的产物,是极其有用的合成中间体。然而,由于具有挑战性的区域选择性,将炔丙基衍生物转化为炔丙基化合物的例子仍然有限。我们使用LaCl 3 ·2LiCl在没有配体的情况下催化格氏试剂的炔丙基化,具有高区域选择性和立体特异性。该方法显示了使用烷基或(杂)芳基格氏试剂和具有不同离去基团的炔基亲电子试剂的广泛底物范围。我们的方案进一步应用于叶毛多辛 B 的正式合成。利用天然丰富且相对无毒的镧催化剂的方法值得探索。
Alcohols react with arenes in the presence of cationic iron(III) porphyrin catalyst. The reaction involves the formation of the C–C bond via dehydration, which is formal Lewis acid catalyzed Friedel–Craftsreaction.
Electrophilic chemistry of propargylic alcohols in imidazolium ionic liquids: Propargylation of arenes and synthesis of propargylic ethers catalyzed by metallic triflates [Bi(OTf)3, Sc(OTf)3, Yb(OTf)3], TfOH, or B(C6F5)3
作者:Gopalakrishnan Aridoss、Viorel D. Sarca、James F. Ponder Jr、Jessica Crowe、Kenneth K. Laali
DOI:10.1039/c0ob00872a
日期:——
formed. Steric influence of the propargylic moiety on substrate selectivity is reflected in the lack of ortho propargylation for phenol and ethylbenzene by using propargylic alcohol Ia, and notable formation of the ortho isomer employing alcohol Ib. In the later case paraselectivity could be increased by running the reaction at r. t. for 10 h. The Bi(OTf)3-catalyzed reaction of 1,3-dimethoxybenzene with
Synthesis and Functionalization of Allenes by Direct Pd‐Catalyzed Organolithium Cross‐Coupling
作者:Jaime Mateos‐Gil、Anirban Mondal、Marta Castiñeira Reis、Ben L. Feringa
DOI:10.1002/anie.201913132
日期:2020.5.11
A palladium-catalyzed cross-coupling between in situ generated allenyl/propargyl-lithium species and arylbromides to yield highly functionalized allenes is reported. The direct and selective formation of allenic products preventing the corresponding isomeric propargylic product is accomplished by the choice of SPhos or XPhos based Pd catalysts. The methodology avoids the prior transmetalation to other