Abstract

The reaction of 1-bromo-3-halo-2-iodobenzene (I; X = Cl) with butyllithium gives 62% (II; X = Cl) similarly reaction of [I; X = F(III)] gave 64% II (X = F). These reactions involve the immediate intermediacy of the halolithiobiphenyl (IV) and the penultimate intermediate (V); V decomps. to give the corresponding benzyne VI which then reacts with addnl. V to give IV. Similarly, reaction of III with butyllithium and gives 79% VII (R = Br) via intermediacy of labile 2-BrC6H4Li (VIII) and V (X = F); VIII decomps. to VI (X = F), at temps. > -125 Deg, which then combines with the more stable V (X = F) to give the immediate intermediate to VII (R = Br), namely VII (R = Li). [on SciFinder (R)]

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