Department of Chemistry, University of California , Berkeley, California 94720, United States.
J Am Chem Soc. 2017 Jan 25;139(3):1325-1329. doi: 10.1021/jacs.6b12569. Epub 2017 Jan 12.
Many site-selective palladium-catalyzed C-H functionalization methods require directing groups. We report here β-carboline amides as intrinsic directing groups for C(sp)-H functionalization. Various substrates including the natural product alangiobussinine and the marinacarboline core structure were functionalized using carboline-directed δ-C(sp)-H alkynylations. This transformation proceeds under mild conditions and is compatible with a wide variety of β-arylethamines. δ-Alkynylation of β-arylethamines via a six-membered palladacycle is favored over γ-C(sp)-H bond functionalization when both positions are accessible. The versatility of β-carboline amides as directing groups is evidenced by other δ-C(sp)-H functionalizations such as alkenylation, arylation, and C-N bond formation.
许多基于钯催化的位点选择性 C-H 官能团化方法都需要导向基团。在此，我们报告β-咔啉酰胺作为 C(sp)-H 官能团化的固有导向基团。利用咔啉导向的 δ-C(sp)-H 炔基化反应，各种底物，包括天然产物阿兰吉布辛宁和海洋咔啉核心结构，都得到了官能化。该转化在温和的条件下进行，并且与各种β-芳基乙胺兼容。当两个位置都可接近时，六元钯环上的β-芳基乙胺的 δ-炔基化优先于 γ-C(sp)-H 键官能团化。β-咔啉酰胺作为导向基团的多功能性还可以通过其他 δ-C(sp)-H 官能团化得到证明，例如烯基化、芳基化和 C-N 键形成。
