Synthesis of 2-Aryloxy-1,3-dienes from Phenols and Propargyl Carbonates

Abstract

A convenient method for the synthesis of 1,3-dienes from readily available compounds is reported. 2-Aryoxy-1,3-dienes are produced stereoselectively by a nickel-catalyzed reaction of propargyl carbonates with phenols. Functional group tolerance is broad to allow iodo, formyl, and boryl groups. The resulting 1,3-dienes are of much synthetic value because they can participate in a wide variety of reactions, including the Diels–Alder reaction.

Transition‐Metal‐Free Synthesis of Electron Rich 1,3‐Dienes via Base Promoted Isomerization of Propargylic Ethers

“…1,3‐Dienes are important building blocks both in organic synthesis, and materials science Therefore, the construction of dienes has attracted considerable attention in synthetic community and numerous methodologies have been developed to provide access to the 1,3‐dienes bearing various functionalities , . However, the approaches to electron rich 1,3‐dienes, such as 2‐oxygenated‐1,3‐butadienes, are still only a few with a remarkably restricted substrate scope . Representative strategies (Scheme ) include olefination of α,β‐unsaturated esters with various reagents to form the 1,3‐dienes, enolization of substituted vinyl ketones to prepare Danishefsky's 1,3‐dienes or surrogates, palladium‐catalyzed cross coupling, isomerization of yne‐carbonyl compounds to conjugated dienecarbonyl compounds with triphenylphosphine .…”

“…Representative strategies (Scheme ) include olefination of α,β‐unsaturated esters with various reagents to form the 1,3‐dienes, enolization of substituted vinyl ketones to prepare Danishefsky's 1,3‐dienes or surrogates, palladium‐catalyzed cross coupling, isomerization of yne‐carbonyl compounds to conjugated dienecarbonyl compounds with triphenylphosphine . Recently, methods involving transition‐metal catalyzed isomerization of alkynes to obtain1,3‐dienes have also been reported and further enrich the arsenal of diene synthesis , . At the same time, both base‐mediated isomerization of propargylic ethers to allenic ethers and base‐mediated allylic isomerization are very well established.…”

Nickel-Catalyzed α-1,3-Dienylation of 1,3-Dicarbonyl Compounds with Propargylic Carbonates

“…We assume that the diene 3 is formed from 1 and 2 through a mechanistic pathway shown in Scheme 3, which is analogous to that previously proposed for the production of 2-phenoxy-1,3dienes from phenols and propargylic carbonates. 3 Initially, propargylic carbonate 2 undergoes oxidative addition onto nickel(0) to furnish -propargylnickel 10 /carbonate ion pair A.…”

“…A currently emerging method is presented by a transition-metal-catalyzed substitution reaction of propargylic (but-2-ynyl and other substituted propargyl) electrophilies with nucleophilic species (path A in Scheme 1). [2][3][4][5] The substituted propargyl group serves as a surrogate of a 1,3-dienyl unit, which is introduced into the nucleophile. This pathway possibly competes with other pathways B-D shown in Scheme 1; 6 (B) substitution at the propargylic position, 7 (C) S N 2′type substitution along with transposition of the -bond forming allenes, 8 and (D) double introduction of the nucleophile.…”

Cooperative Ni/Cu‐Catalyzed Asymmetric Propargylic Alkylation of Aldimine Esters

“…[9b] Recently, the Murakami group disclosed a nickel-catalyzed reaction of propargyl carbonates with phenols to synthesize 2-aryloxy-1,3-dienes. [11] However, the discovery of catalytic asymmetric methods with an inner alkyne precursor in a predictable manner to generate the corresponding propargylated products via propargylic carbonates remains a formidable challenge (Scheme 1 B). [3] In recent years, cooperative catalysis has emerged as an effective and reliable strategy to enable a series of new enantioselective transformations.…”