Dearomative [3,3]-Claisen Rearrangement of 2-Indolyl Alcohols: An Efficient and General Protocol for Synthesizing 3,3-Disubstituted Indolines and Related Indole Alkaloids.

Dearomative reactions of indoles have long been a focal point of research in organic synthesis due to their ability to transform planar molecules into three-dimensional structures. Among these reactions, the dearomative indolic [3,3]-Claisen rearrangement stands out, though it has been largely limited to two substrate classes: 2-allyloxy indoles and 3-indolyl alcohols. Herein, we report a practical and reliable dearomative Meerwein-Eschenmoser-Claisen rearrangement of 2-indolyl alcohols, providing an innovative solution for the efficient construction of the widely observed structural unit of 3,3-disubstituted indolines, prevalent in natural products and pharmaceuticals. This synthetic methodology features simple reaction conditions, broad substrate scope, good E/Z selectivity for products, and excellent chirality transfer from starting materials. The robustness of this methodology is demonstrated via the concise asymmetric total synthesis of the structurally complex alkaloid minfiensine, wherein the success of the total synthesis hinges on the strategic transformation of the dearomative indolic [3,3]-Claisen rearrangement coupled with the palladium-catalyzed regioselective α-vinylation of carbonyl compounds.