Morita–Baylis–Hillman‐Type [3,3]‐Rearrangement: Switching from<i>Z</i>‐ to<i>E</i>‐Selective α‐Arylation by New Rearrangement Partners
Lei Zhang, Wangzhen Bao, Yuchen Liang, Wenjing Pan, Dongyang Li, Lichun Kong, Zhixiang Wang, Bo Peng
Abstract
α-aryl α,β-unsaturated carbonyls represent an important class of derivatizable synthetic intermediates, however, the synthesis of such compounds still remains a challenge. Recently, we showcased a novel Z-selective α-arylation of α,β-unsaturated nitriles with aryl sulfoxides via [3,3]-rearrangement involving an Morita-Baylis-Hillman (MBH) process. Herein, we demonstrate the feasibility of reversing the stereoselectivity of such MBH-type [3,3]-rearrangement by switching to a new pair of rearrangement partners consisting of aryl iodanes and α,β-unsaturated oxazolines. As a result, the two protocols complement each other in approaching E- or Z-α-aryl α,β-unsaturated carbonyl derivatives. Mechanistic studies reveal a possible reaction pathway and provide an explanation for the opposite stereoselectivities.