Chiral Anion‐Induced Catalytic Asymmetric Direct Dehydrative Coupling of 3‐Vinylindoles and 3‐Indolylmethanols

Abstract

The catalytic direct dehydrative coupling of an alkene with an alcohol is one of the most straightforward and green strategies for the formation of Csp2−Csp2 bonds. However, previously reported studies have only dealt with achiral reactions. Here, we describe chiral Brønsted acid‐catalyzed direct catalytic asymmetric dehydrative coupling reactions of 3‐vinylindoles and 3‐indolylmethanols. Various structurally diverse indole compounds were prepared in good to excellent yields, with good to excellent stereoselectivities.magnified image

Brønsted Acid‐Catalysed Dehydrative Substitution Reactions of Alcohols

“…[47] In 2019, Guo and co-workersf ound that 3-vinylindoles are also good nucleophiles for addition into 3-indolylmethanols. [48] The optimal conditions for the reaction of 35 with 36 use imidodiphosphoric acid 37 (2 mol %) as catalyst, giving product 38 in high yield with excellent stereoselectivity (Scheme 20).…”

Organocatalytic Asymmetric [2 + 4] Cycloadditions of 3-Vinylindoles with ortho-Quinone Methides

“…As shown in Figure 1, 3-vinylindoles exhibit versatile reactivities and participate in four main types of organocatalytic asymmetric reactions. Namely, 3-vinylindoles act as dienes in asymmetric [4 + 2] cycloaddition (Figure 1a) [8][9][10][11][12], as mono-olefins in asymmetric [2 + n] cycloaddition (Figure 1b) [13][14][15][16][17][18][19][20][21][22][23], as electrophiles in asymmetric addition reaction (Figure 1c) [24][25][26][27], and as nucleophiles in asymmetric alkenylation (Figure 1d) [28,29]. Among these reactions, organocatalytic asymmetric [2 + n] cycloaddition of 3-vinylindoles as mono-olefins has proven to be an important reaction (Figure 1b) to efficiently synthesize indole-containing heterocycles with optical purity [30,31].…”