Catalytic [3+3] Annulation of <scp>β‐Ketoethers</scp> and Cyclopropenones <i>via</i> C(sp<sup>3</sup>)—O/C—C Bond Cleavage under <scp>Transition‐Metal</scp> Free Conditions
Dachang Bai, Junyan Chen, Bingbing Zheng, Xueyan Li, Junbiao Chang
Abstract
Main observation and conclusion The efficient cleavage of carbon‐oxygen (C—O) bond is highly important for the transformation of oxygen‐rich biomass and industry chemicals. Herein, an efficient [3+3] annulation of β‐ketoethers with cyclopropenones in the presence of catalytic base has been developed, which proceeds through the C(sp 3 )—O bonds cleavage in β‐ketoethers and C—C bond cleavage in cyclopropenones under transition‐metal free conditions. The cleavage of C(sp 3 )—O bonds in alkyl alkyl ethers and aryl alkyl ethers was realized. The reaction featured excellent functional group compatibility and chemoselectivity, affording various 2‐pyrones in good to excellent yields under mild conditions and simple operation.