Zhao Gaoyuan, Lim Sanghyun, Musaev Djamaladdin G, Ngai Ming-Yu
Department of Chemistry, State University of New York, Stony Brook, New York, 11794, United States.
Cherry L. Emerson Center for Scientific Computation, and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States.
J Am Chem Soc. 2023 Apr 5. doi: 10.1021/jacs.2c11867.
Allyl carboxylates are useful synthetic intermediates in a variety of organic transformations, including catalytic nucleophilic/electrophilic allylic substitution reactions and 1,2-difunctionalization reactions. However, the catalytic 1,3-difunctionalization of allyl carboxylates remains elusive. Herein, we report the first photoinduced, phosphine-catalyzed 1,3-carbobromination of allyl carboxylates, affording a range of valuable substituted isopropyl carboxylates (sIPC). The transformation has broad functional group tolerance, is amenable to the late-stage modification of complex molecules and gram-scale synthesis, and expands the reaction profiles of allyl carboxylates and phosphine catalysis. Preliminary experimental and computational studies suggest a non-chain-radical mechanism involving the formation of an electron donor-acceptor complex, 1,2-radical migration (RaM), and Br-atom transfer processes. We anticipate that the 1,2-RaM reactivity of allyl carboxylates and the phosphine-catalyzed radical reaction will both serve as a platform for the development of new transformations in organic synthesis.
羧酸烯丙酯是多种有机转化中有用的合成中间体，包括催化亲核/亲电烯丙基取代反应和1,2-双官能化反应。然而，羧酸烯丙酯的催化1,3-双官能化反应仍然难以实现。在此，我们报道了首例光诱导、膦催化的羧酸烯丙酯的1,3-碳溴化反应，得到了一系列有价值的取代羧酸异丙酯（sIPC）。该转化具有广泛的官能团耐受性，适用于复杂分子的后期修饰和克级规模合成，并扩展了羧酸烯丙酯和膦催化的反应类型。初步的实验和计算研究表明，该反应涉及电子供体-受体复合物的形成、1,2-自由基迁移（RaM）和溴原子转移过程的非链自由基机理。我们预计，羧酸烯丙酯的1,2-RaM反应性和膦催化的自由基反应都将成为有机合成中新型转化反应开发的平台。
