A highly efficient route to C-3 alkyl-substituted indoles via completely metal-free catalytic transfer hydrogenation of 3-indolemethanols was developed. This process proceeds via vinylogous iminium intermediates formed in situ in the presence of Brønsted acids, and Hantzsch ester is used as the reductant. The reduction works extremely well with a large substrate scope, and the yields exceed 90% in
开发了通过3-
吲哚甲醇的完全无
金属催化转移加
氢制取C-3烷基取代的
吲哚的高效途径。该过程是通过在布朗斯台德酸的存在下原位形成的
乙烯基亚胺基
中间体进行的,汉茨
酯用作还原剂。在较大的基材范围内,还原效果非常好,几乎在所有情况下,成品率均超过90%。