Lanthanide-Catalyst-Mediated Tandem Double Intramolecular Hydroalkoxylation/Cyclization of Dialkynyl Dialcohols: Scope and Mechanism
作者:SungYong Seo、Tobin J. Marks
DOI:10.1002/chem.200903027
日期:——
hydroalkoxylation/cyclization is first‐order in [catalyst] and zero‐order in [alkynyl alcohol], as is observed for the organolanthanide‐catalyzed hydroamination/cyclization of aminoalkenes, aminoalkynes, and aminoallenes, and the intramolecular single‐step hydroalkoxylation/cyclization of alkynyl alcohols. An ROH/ROD kinetic isotope effect of 0.82(0.02) is observed for the tandem double hydroalkoxylation/cyclization
[LN N(森的一般类型的镧系元素的有机络合物3)2 } 3 ](Ln为La,Sm或Y,Lu)的作为有效的预催化剂的快速,外切选择性和高度区域选择性的串联双分子内双羟基烷氧基化/环化伯和仲二炔基二元醇,生成相应的双环外烯醇醚。转化具有高度选择性,其产物与常规过渡金属或其他催化剂通常产生的产物明显不同,并且某些底物的周转频率太大,无法准确确定。末端炔醇加氢烷氧基化/环化的速度明显快于内部炔醇的速度,理由是空间需求主导着环化过渡态。内部二炔基二元醇的加氢烷氧基化/环化可提供出色的E选择性。炔基二元醇加氢烷氧基化/环化的速率定律在[催化剂]中为一阶,在[炔醇]中为零阶,正如有机镧系元素催化的氨基烯,氨基炔和氨基丙烯的加氢胺化/环化以及分子内单炔醇的加氢烷氧基化/环化。串联双加氢烷氧基化/环化的ROH / ROD动力学同位素效应为0.82(0.02)。这些机械数据牵累周转限制性的插入Ç Ç不饱和度到LN