Diastereoselective [2+2+1] Hydrative Annulation of Phenol‐Linked 1,6‐Enynes with Acetylenes Through Rhodium Catalysis: A Rapid Access to Cyclopenta[b]benzofuranols

Abstract

An unprecedented [2+2+1] hydrative annulation of 1,6‐enynes with terminal alkynes is achieved using catalytic cationic Rh(I). Thus, a modular assembly of cyclopenta[b]benzofuranols with two consecutive quarternary stereocenters is achieved from readily available alkynes. The reaction is proposed to go through a sequence of 5‐membered rhoda‐cycle formation, regioselective acetylene insertion, 1,5 H‐shift, substrate controlled stereoselective addition of water molecule followed by 1,2‐rhodium migration gave contracted rhoda‐cycle D and reductive elimination. Necessary control/labelling experiments were conducted to gain insight in to the mechanism.

Access to phosphorus-containing cyclopenta[b]benzofuranols via a serendipitous cascade reaction promoted by a bifunctional phosphonium salt

“…5 Since then, a handful of further exciting outcomes have been achieved for the construction of this class of compounds. 6,7 However, despite these advances, most of the existing approaches still show flaws, such as the need to perform substrate prefunctionalization, low atomic economy, and harsh reaction conditions. Therefore, developing a practical, green and novel strategy for concise and efficient construction of densely functionalized cyclopenta[ b ]benzofurans and their derivatives—while challenging—remains highly desirable.…”

Synthesis of cyclopenta[b]benzofurans via biomimetic oxidative phenol–enamine [3 + 2] cycloaddition

“…Over the past few decades, some leading techniques for the synthesis of these scaffolds have been documented, a majority of which were achieved through [3 + 2] photocycloadditions, 4 Nazarov cyclization, 5 radical cyclization, 5 e , f and so on. 6 In the past decade, there has been great progress in the applications of copper- and palladium-catalyzed cross-coupling of aryl halides with various synthons for the assembly of these compounds. 6…”

“…6 In the past decade, there has been great progress in the applications of copper- and palladium-catalyzed cross-coupling of aryl halides with various synthons for the assembly of these compounds. 6…”

Palladium-Catalyzed Carbo-Aminative Cyclization of 1,6-Enynes: Access to Napthyridinone Derivatives

“…The intriguing reactive nature of 1,6-enynes together with our interest in the exploration of the novel reactivity of activated alkynes stirred us to devise a concise and pragmatic method for novel N-heterocycles. Thus we report herein an annulative cyclization of 1,6-enynes with iodoanilines to construct napthyridinone derivatives (Scheme d).…”