105591-43-3Relevant academic research and scientific papers
Accelerating effect of meta substituents in the ester-mediated nucleophilic aromatic substitution reaction
Hattori, Tetsutaro,Takeda, Ayanobu,Suzuki, Kenji,Koike, Nobuyuki,Koshiishi, Eiji,Miyano, Sotaro
, p. 3661 - 3671 (2007/10/03)
The ester-mediated nucleophilic aromatic substitution (SNAr) reaction of 2-methoxybenzoic ester 1 with Grignard reagents 11 is greatly accelerated by introduction of a methoxy or halo substituent at the 3-position of the benzoate ring (7-10). The substituent effects of these groups at the 3-position are compared with those at the 5-position to suggest that the activation mechanism of the methoxy substituent is different from that of the halo substituent; the ligating ability of the 3-methoxy group plays a crucial role in enhancing the reactivity of the 2-methoxy moiety, while the electron-withdrawing ability is more important in the case of the halo groups. It has also been found that introduction of an additional methoxy substituent at the meta-position (33, 34) enables the SNAr methoxy-displacement reaction even at the para-position to the ester activator. The accelerating effect of the 3-bromo substituent is advantageously utilized for regioselective allylation of 3-bromo-2,6-dimethoxybenzoic ester 55 at the 2-position to provide an easy access to a multisubstituted naphthol 59, which is a key compound for the syntheses of michellamines A-C and the related naphthylisoquinoline alkaloids.
Selective Demethylative Cyclisation of 2-Methoxy-allylbenzenes
Devakumar, C.,Mukerjee, S. K.
, p. 368 - 372 (2007/10/02)
Treatment of 3-substituted 2-methoxyallylbenzenes with dry HBr in CHCl3 causes selective demethylative cyclisation to give 7-substituted 2-methyl-2,3-dihydrobenzofurans.The reaction involves mutual participation of allyl and 2-methoxyl groups and is sterically accelerated by substituents vicinal to OCH3.The reaction does not take place in high dielectric solvents such as DMF or DMSO.A propable mechanism envisaging a non-classical ionic transition state is proposed and the synthetic utility of this reaction is also demonstrated.
