176386-54-2Relevant articles and documents
Process for the preparation of functionalised benzocyclobutenes, and application in the synthesis of ivabradine and addition salts thereof with a pharmaceutically acceptable acid
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Page/Page column 4, (2010/02/17)
Process for the preparation of compounds of formula (IV): wherein R1, R2, R3 and R4, which may be identical or different, each represent a hydrogen atom, a linear or branched (C1-C6)alkyl group, a linear or branched (C1-C6)alkoxy group, a fluorine atom, a chlorine atom, a protected amine group, a protected hydroxyl group, an alkoxycarbonyl group in which the alkoxy group is linear or branched (C1-C6), or a CF3 group, or R1═R4═H and R2 and R3 together with the carbon atoms carrying them form a 1,3-dioxolane group, R5 represents a saturated or unsaturated, linear or branched (C1-C6)alkyl group, a linear or branched (C1-C6)hydroxyalkyl group in which the hydroxyl function is protected, or a CO2R7 group in which R7 is a linear or branched (C1-C6)alkyl group,R6 represents a cyano group or a CO2R8 group in which R8 is a linear or branched (C1-C6)-alkyl group.Application in the synthesis of ivabradine, addition salts thereof with a pharmaceutically acceptable acid and hydrates thereof.
Synthesis of benzocyclobutenes by palladium-catalyzed C-H activation of methyl groups: Method and mechanistic study
Chaumontet, Manon,Piccardi, Riccardo,Audic, Nicolas,Hitce, Julien,Peglion, Jean-Louis,Clot, Eric,Baudoin, Olivier
supporting information; experimental part, p. 15157 - 15166 (2009/03/12)
An efficient catalytic system has been developed for the synthesis of benzocyclobutenes by C-H activation of methyl groups. The optimal conditions employed a combination of Pd(OAc)2 and PtBu3 as catalyst, K2CO3 as the base, and DMF as solvent. A variety of substituted BCB were obtained under these conditions with yields in the 44-92% range, including molecules that are hardly accessible by other methods. The reaction was found limited to substrates bearing a quaternary benzylic carbon, but benzocyclobutenes bearing a tertiary benzylic carbon could be obtained indirectly from diesters by decarboxylation. Reaction substrates bearing a small substituent para to bromine gave an unexpected regioisomer that likely arose from a 1,4-palladium migration process. The formation of this "abnormal" regioisomer could be suppressed by introducing a larger subsituent para to bromine. DFT(B3PW91) calculations on the reaction of 2-bromo-tert-butylbenzene with Pd(PtBu3) with different bases (acetate, bicarbonate, carbonate) showed the critical influence of the coordination mode of the base to induce both an easy C-H activation and to allow for a pathway for 1,4-palladium migration. Carbonate is shown to be more efficient than the two other bases because it can abstract the proton easily and at the same time maintain κ1-coordination without extensive electronic reorganization.
Phase-transfer Catalysis: A Convenient Tool for the Functionalization of Benzocyclobutene-1-carbonitrile
Fedorynski, Michal,Zielinski, Marek,Jonczyk, Andrzej
, p. 36 - 37 (2007/10/03)
Benzocyclobutene-1-carbonitrile 1 is further functionalized at the 1-position by reaction with electrophilic compounds in the presence of concentrated aqueous alkali metal hydroxides and tetra-n-butylammonium bromide as a phase-transfer catalyst.
