a-aryl a,b-unsaturated carbonyls represent an important class of derivatizable synthetic intermediates,h owever,the synthesis of such compounds still remains achallenge. Recently,weshowcased anovel Z-selective a-arylation of a,bunsaturated 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 an ew pair of rearrangement partners consisting of aryl iodanes and a,b-unsaturated oxazolines.A saresult, the two protocols complement each other in approaching E-or Z-aaryl a,b-unsaturated carbonyl derivatives.M echanistic studies reveal apossible reaction pathway and provide an explanation for the opposite stereoselectivities.
The [3,3]-rearrangement of aryl iodanes with α,β-unsaturated oxazolines has been developed by merging Morita-Baylis-Hillman (MBH) process into the rearrangement reaction. The method allows for the exclusively E-selective synthesis of a wide variety of valuable α-aryl α,β-unsaturated oxazolines which can be difficult to synthesize with other known methods. Experimental and computational mechanistic studies unraveled that the reaction proceeds via the assembly of both coupling partners followed by MBH-type addition to form rearrangement precursor, [3,3]-rearrangement, and stepwise E1cb-elimination. The E-selectivity of the reaction is favored both kinetically and thermodynamically.
a-aryl a,b-unsaturated carbonyls represent an important class of derivatizable synthetic intermediates,h owever,the synthesis of such compounds still remains achallenge. Recently,weshowcased anovel Z-selective a-arylation of a,bunsaturated 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 an ew pair of rearrangement partners consisting of aryl iodanes and a,b-unsaturated oxazolines.A saresult, the two protocols complement each other in approaching E-or Z-aaryl a,b-unsaturated carbonyl derivatives.M echanistic studies reveal apossible reaction pathway and provide an explanation for the opposite stereoselectivities.
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