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)]
Note:
CAN 138:287078 22-4 Physical Organic Chemistry Institut de chimie moleculaire et biologique Ecole Polytechnique Federale,Lausanne,Switz. Journal 1433-7851 written in English. 41423-20-5; 507242-01-5; 507242-06-0; 507242-11-7; 507242-16-2; 507242-21-9; 507242-27-5; 507242-32-2; 507242-38-8; 507242-43-5 Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (addn. of benzynes with mechanistic reaction intermediate; aryne route to biaryls featuring uncommon substituent patterns); 462-80-6 (o-Benzyne); 7048-96-6; 62209-91-0; 85683-73-4 Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (aryllithiums addn. reaction with mechanistic reaction intermediate; aryne route to biaryls featuring uncommon substituent patterns); 109-72-8; 583-53-9; 583-55-1; 15810-15-8 (9,10-Dibromophenanthrene) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (aryne route to biaryls featuring uncommon substituent patterns); 19821-80-8P; 450412-28-9P; 450412-29-0P; 507241-77-2P Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), PROC (Process), RACT (Reactant or reagent) (aryne route to biaryls featuring uncommon substituent patterns); 13029-09-9 Role: FMU (Formation, unclassified), FORM (Formation, nonpreparative) (aryne route to biaryls featuring uncommon substituent patterns); 1073-06-9 (1-Bromo-3-fluorobenzene) Role: RCT (Reactant), RACT (Reactant or reagent) (aryne route to biaryls featuring uncommon substituent patterns); 39655-12-4P; 507241-51-2P; 507241-65-8P; 507241-69-2P; 507241-82-9P Role: SPN (Synthetic preparation), PREP (Preparation) (aryne route to biaryls featuring uncommon substituent patterns); 109-65-9 (Butyl bromide) Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (bromine-lithium exchange of aryllithium with mechanistic reaction intermediate; aryne route to biaryls featuring uncommon substituent patterns); 108-36-1 (1,3-Dibromobenzene) Role: RCT (Reactant), RACT (Reactant or reagent) (conversion to 1,3-dibromo-2-iodobenzene; aryne route to biaryls featuring uncommon substituent patterns); 108-37-2 (1-Bromo-3-chlorobenzene) Role: RCT (Reactant), RACT (Reactant or reagent) (conversion to 1-bromo-3-chloro-2-iodobenzene; aryne route to biaryls featuring uncommon substituent patterns); 7553-56-2 (Iodine) Role: RCT (Reactant), RACT (Reactant or reagent) (conversion to 1-bromo-3-fluoro-2-iodobenzene; aryne route to biaryls featuring uncommon substituent patterns); 16523-54-9 (Chlorodicyclohexylphosphine) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (conversion to 2,2'-bis(dicyclohexylphosphino)-6-fluorobiphenyl; aryne route to biaryls featuring uncommon substituent patterns); 108-18-9 (Diisopropylamine) Role: RGT (Reagent), RACT (Reactant or reagent) (formation in conversion to 1-bromo-3-fluoro-2-iodobenzene; aryne route to biaryls featuring uncommon substituent patterns); 4111-54-0 (Lithium diisopropylamide) Role: FMU (Formation, unclassified), RGT (Reagent), FORM (Formation, nonpreparative), RACT (Reactant or reagent) (in formation of 1-bromo-3-fluoro-2-iodobenzene; aryne route to biaryls featuring uncommon substituent patterns); 542-69-8 (Butyl iodide) Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (iodine-lithium exchange of aryllithium with mechanistic reaction intermediate; aryne route to biaryls featuring uncommon substituent patterns); 33432-66-5 (2-Bromophenyl lit ium) Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (lithium bromide elimination from labile mechanistic reaction intermediate; aryne route to biaryls featuring uncommon substituent patterns); 507241-87-4P Role: PRP (Properties), SPN (Synthetic preparation), PREP (Preparation) (min. rotational barrier; aryne route to biaryls featuring uncommon substituent patterns)
