Meta-and Para-Difunctionalization of Arenesvia an Ortho-Magnesiation and a SubsequentSulfoxide-Magnesium Exchange

; Highly functionalized 1,2,4-trisubstituted arenes can be prepared on large scale by a two-step sequence, triggered by an aryl sulfoxide group. In the first step, the sulfoxide moiety acts as a metalation directing group, allowing a smooth magnesiation with tmp-MgCl-LiCl. After a quenching reaction with an electrophile, the resulting sulfoxide is converted with i-PrMgCl·LiCl into a second magnesium reagent (sulfoxide-magnesium exchange), which can be trapped with various electrophiles. The highly chemoselective tmpMgCl·LiCl and i-PrMgCl·LiCl are compatible with a broad range of functional groups (FG = F, Cl, CF 3 , CN, CO 2 t-Bu, alkynyl).