85370-71-4Relevant academic research and scientific papers
Directed Ortho Metalation of N,N-Diethylbenzamides. Silicon Protection of Ortho Sites and the o-Methyl Group
Mills, Robert J.,Taylor, Nicholas J.,Snieckus, Victor
, p. 4372 - 4385 (2007/10/02)
New general methodology of value in aromatic chemistry based on silicon protection of preferred ortho metalation sites in benzamides and o-methyl groups in o-toluamides (1, 2, Scheme I) is described.According to these methodologies, routes (Scheme II and V) to 1,2,5-, 1,2,4,5-, and 1,2,3-substituted aromatics with a variety of functionalities and oxidation states have been developed (Tables I and II).These tactics are used for the synthesis of difficult to access halo (10a-b, Scheme III) and methyl (21,25, Scheme VI) heterocycles.Ipso bromodesilylation reactions with bromine lead regiospecifically to o-bromobenzamides (12a,c, 14, Scheme IV).Walk-around-the-ring metalation processes provide highly substituted aromatics 27, 28, 29, and 30 (Scheme VII); the X-ray structure of the hexasubstituted derivative 30 shows a significant puckering of the aromatic ring.Cesium fluoride induced carbodesilylation of o-silylbenzamides with benzaldehyde affords, after TsOH cyclization, phthalides (31a-c, Scheme VIII) and constitutes a neutral alternative to the directed ortho metalation approach. α- and α,α-silylated o-toluamides are used in fluoride-mediated carbodesilylation (34a,d, Scheme IX) and desilylative Peterson olefination (35, Scheme X) procedures, respectively.The utility of α-silylated o-toluamide for the synthesis of a tetralin (38, Scheme XI) via an o-quinodimethane species is given.
Ortho-Lithiated Tertiary Benzamides. Chain Extension via o-Toluamide Anion and General Synthesis of Isocoumarins Including Hydrangenol and Phyllodulcin
Watanabe, Mitsuaki,Sahara, Masanori,Kubo, Masaki,Furukawa, Sunao,Billedeau, R. J.,Snieckus, V.
, p. 742 - 747 (2007/10/02)
Lithiation of N,N-diethyl-2-methylbenzamide (2a) followed by condensation with aromatic aldehydes and basic hydrolysis leads to 3-aryl-3,4-dihydroisocoumarins 4 in modest overall yields.Adoption of this methodology to N,N-dimethyl-2-methyl-6-methoxybenzamide (7b) provides isocoumarins 9a and 9b which by selective demethylation procedures yields hydrangenol (10a) and phyllodulcin (10c), naturally occurring isocoumarins of pharmacological interest.A one-pot, abbreviated procedure for the preparation of both 9a and 9b starting with N,N-Dimethyl-2-methoxybenzamide (6c) is also described.
Directed Metalation of Tertiary Benzamides. Silicon Protection of Ortho Sites and Ortho Methyl Groups
Mills, R. J.,Snieckus, V.
, p. 1565 - 1568 (2007/10/02)
Metalation of 2-trimethylsilyl or 2-bis(trimethylsilyl)methyl benzamides occurs selectively at the 6-position, providing regiospecific routes to various trisubstituted benzenes.
