Buttressing effects rerouting the deprotonation and functionalization of 1,3-dichloro- and 1,3-dibromobenzene
A systematic comparison between 1,3-difluorobenzene, 1,3-dichlorobenzene, and 1,3-dibromobenzene did not reveal major differences in their behavior towards strong bases such as lithium diisopropylamide or lithium 2,2,6,6-tetramethylpiperidide. Thus, all 2,6-dihalobenzoic acids are directly accessible by consecutive treatment with a suitable base and dry ice. In contrast, (2,6-dichlorophenyl)- and (2,6-bromophenyl)triethylsilane undergo deprotonation at the 5-position (affording the 4-carboxy derivs. and the 3,5-dihalobenzoic acids after deprotection), whereas the 1,3-difluoro analog is known to react at the 4-position. The 2,4-dihalobenzoic acids were selectively prepd. from either the silanes by bromination at the 4-position, metalation and carboxylation of the neighboring position, followed by desilylation and debromination or the 1,3-dihalo-2-iodobenzenes by base-promoted migration of iodine to the 4-position followed by iodine/magnesium permutation and subsequent carboxylation. [on SciFinder (R)]
WOS:000187126800019
2003
23
4625
4629
CAN 140:128122 25-17 Benzene, Its Derivatives, and Condensed Benzenoid Compounds Institut de Chimie Moleculaire et Biologique, Ecole Polytechnique Federale,Lausanne,Switz. Journal 1434-193X written in English. 108-36-1 (1,3-Dibromobenzene); 541-73-1 (1,3-Dichlorobenzene); 19393-94-3 (2,4-Dibromo-1-iodobenzene) Role: RCT (Reactant), RACT (Reactant or reagent) (the deprotonation and functionalization of 1,3-dichloro- and 1,3-dibromobenzene); 601-84-3P (2,6-Dibromobenzoic acid); 626-39-1P (1,3,5-Tribromobenzene); 633-12-5P (2,4,6-Tribromobenzoic acid); 20082-66-0P; 650598-41-7P; 650598-42-8P; 650598-43-9P; 650598-44-0P; 650598-45-1P; 650598-46-2P (2,6-Dibromophenyltriethylsilane); 650598-47-3P; 650598-48-4P; 650598-49-5P; 650598-50-8P; 722540-83-2P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (the deprotonation and functionalization of 1,3-dichloro- and 1,3-dibromobenzene); 50-30-6P (2,6-Dichlorobenzoic acid); 50-84-0P (2,4-Dichlorobenzoic acid); 51-36-5P (3,5-Dichlorobenzoic acid); 611-00-7P (2,4-Dibromobenzoic acid); 618-58-6P (3,5-Dibromobenzoic acid); 194084-84-9P (2,6-Diiodobenzoic acid) Role: SPN (Synthetic preparation), PREP (Preparation) (the deprotonation and functionalization of 1,3-dichloro- and 1,3-dibromobenzene)
REVIEWED
EPFL