20935-62-0Relevant articles and documents
Sassa et al.
, p. 5703 (1968)
Pd-Catalyzed ipso, meta-Dimethylation of ortho-Substituted Iodoarenes via a Base-Controlled C-H Activation Cascade with Dimethyl Carbonate as the Methyl Source
Wu, Zhuo,Wei, Feng,Wan, Bin,Zhang, Yanghui
supporting information, p. 4524 - 4530 (2021/05/04)
A methyl group can have a profound impact on the pharmacological properties of organic molecules. Hence, developing methylation methods and methylating reagents is essential in medicinal chemistry. We report a palladium-catalyzed dimethylation reaction of ortho-substituted iodoarenes using dimethyl carbonate as a methyl source. In the presence of K2CO3 as a base, iodoarenes are dimethylated at the ipso- and meta-positions of the iodo group, which represents a novel strategy for meta-C-H methylation. With KOAc as the base, subsequent oxidative C(sp3)-H/C(sp3)-H coupling occurs; in this case, the overall transformation achieves triple C-H activation to form three new C-C bonds. These reactions allow expedient access to 2,6-dimethylated phenols, 2,3-dihydrobenzofurans, and indanes, which are ubiquitous structural motifs and essential synthetic intermediates of biologically and pharmacologically active compounds.
Boron Trichloride as a Selective Demethylating Agent for Hindered Ethers: a Synthesis of the Phytoalexins α- and β-Pyrufuran, a Synthesis of Tri-O-methylleprolomin and its Demethylation
Carvalho, Christopher F.,Russo, Albert V.,Sargent, Melvyn V.
, p. 777 - 792 (2007/10/02)
Boron trichloride has been found to be an efficient reagent for the selective cleavage of sterically hindered methoxy groups in methoxyarenes.The scope and utility of this reaction are explored with examples drawn from derivatives of benzene, naphtalene, 9,10-dihydrophenanthrene and dibenzofuran.The method is applied to the synthesis of the phytoalexins α- (56) and β-pyrofuran (58) (1,3,4-trimethoxydibenzofuran-2-ol and 1,2,4-trimethoxydibenzofuran-3-ol).A synthesis of tri-O-methylleprolomin (61), a derivative of the unusual lichen metabolite leprolomin (60), is described and its demethylation with boron trichloride is studied.