Sun Dandan, Rajeshkumar Thayalan, Li Yifan, Xu Jiaxin, Chen Runkai, Wan Zhaohua, Lv Zongchao, Maron Laurent, Chen Yi-Hung
Institute for Advanced Studies (IAS), Wuhan University, Wuhan, Hubei 430072, People's Republic of China.
LPCNO, CNRS & INSA, Université Paul Sabatier, 135 Avenue de Rangueil, 31077 Toulouse, France.
Org Lett. 2023 Sep 15;25(36):6730-6735. doi: 10.1021/acs.orglett.3c02600. Epub 2023 Sep 6.
Transition-metal-catalyzed cross-coupling of propargylic electrophiles and Grignard reagents provides densely functionalized products that are extremely useful synthetic intermediates. However, examples of conversion of propargylic derivatives to form propargyl compounds remain limited due to the challenging regioselectivity. We use LaCl·2LiCl to catalyze propargylation of Grignard reagents in the absence of ligand in high regioselectivity and stereospecificity. The approach shows a wide substrate scope using alkyl or (hetero)aryl Grignard reagents and alkynyl electrophiles with different leaving groups. Our protocol was further applied for the formal synthesis of frondosin B. It is worth exploring methodologies utilizing the naturally abundant and relatively nontoxic lanthanum catalysts.
过渡金属催化的炔丙基亲电试剂与格氏试剂的交叉偶联反应可提供具有密集官能团化的产物，这些产物是极为有用的合成中间体。然而，由于区域选择性具有挑战性，将炔丙基衍生物转化为炔丙基化合物的实例仍然有限。我们使用LaCl·2LiCl在无配体的情况下以高区域选择性和立体专一性催化格氏试剂的炔丙基化反应。该方法使用烷基或（杂）芳基格氏试剂以及带有不同离去基团的炔基亲电试剂时显示出广泛的底物范围。我们的方案进一步应用于叶苔素B的形式合成。利用天然丰富且相对无毒的镧系催化剂的方法值得探索。
