Regio‐ and Diastereoselective Organo‐Zinc‐Promoted Arylation of trans‐2,3‐Diaryloxiranes by Arylboronic Acids: Stereoselective Access to trans‐2,3‐Diphenyl‐2,3‐dihydrobenzofuran

ortho‐Oxo substituted trans 2,3‐diaryloxiranes were regio‐ and stereoselectively arylated by arylzinc reagents, obtained from the corresponding boronic acids by B–Zn exchange. The reaction was quite general, irrespective to the aryl nucleophile and proceeded via a ring opening at the α‐carbon with respect to the substituted aryl ring. The stereoselectivity was from high to complete toward the alcohol resulted from retention of configuration at the electrophilic carbon. The method allowed a direct and high yielding access to trans 2,3‐diphenyl‐2,3‐dihydrobenzofuran, which is a key structural motif in resveratrol dimers as viniferins. The use of enantioenriched starting diaryloxiranes resulted in no loss of stereochemical integrity in the final trans 2,3‐dihydrobenzofuran, which was characterized for the first time in enantioenriched form. The ortho‐oxo substituted trans 2,3‐diaryloxiranes were regio‐ and stereoselectively arylated by arylzinc reagents, obtained from the corresponding boronic acids by B–Zn exchange. The method allowed a direct and high yielding access to trans 2,3‐diphenyl 2,3‐dihydro benzofuran. The use of enantioenriched starting diaryl oxiranes resulted in no loss of stereochemical integrity in the final trans 2,3‐dihydrobenzofuran.