81698-82-0Relevant academic research and scientific papers
Effect of π-electron delocalization on tautomeric equilibria - Benzoannulated 2-phenacylpyridines
Gawinecki, Ryszard,Kolehmainen, Erkki,Loghmani-Khouzani, Hossein,O?mia?owski, Borys,Lovász, Tamás,Rosa, Pavel
, p. 2817 - 2824 (2007/10/03)
Most benzoannulated 2-methylpyridines react with phenyllithium and substituted alkyl benzoates to give the corresponding 2-phenacylpyridines. 3-Methylisoquinoline is transformed into 2-benzoyl-3-methyl-1-phenyl-1,2- dihydroisoquinoline under these conditions, but replacement of phenyllithium with lithium isopropylcyclohexylamide is effective for production of 3-phenacylisoquinolines. Except in the cases of some substituted 6-phenacylphenanthridines, tautomeric mixtures of benzoannulated 2-phenacylpyridines in chloroform solution always contain the ketimine forms. (Z)-2-(2-Hydroxy-2-phenylvinyl)pyridine (enolimine) forms also contribute if the pyridine ring is not benzoannulated or if such annulation is at positions 4,5. On the other hand, (Z)-2-benzoylmethylene-1,2-dihydropyridine (enaminone) forms exist in equilibrium with the ketimine tautomers if the pyridine ring is benzoannulated at positions 3,4 or 5,6, or at both of these locations. As well as the effectiveness of π-electron delocalization, other effects, such as the strength of the intramolecular hydrogen bonding, should also be considered in order to infer the tautomeric preferences. Strongly electron-donating substituents were found to stabilize the ketimine forms in each series. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Studies on Intramolecular Cycloaddition Reactions of Some Isoquinolinium Salts
Gisby, Graham P.,Sammes, Peter G.,Watt, Robert A.
, p. 249 - 256 (2007/10/02)
Thermally-induced intramolecular addition reactions of isoquinolinium derivatives bearing an alkenyl side-chain have been studied.Cycloadditions can occur across the isolated olefinic bond and the 1,4-positions of the isoquinolinium system to produce tetracyclic adducts.The chemistry of these adducts is compared with that of cycloadducts produced in intramolecular additions.Preparation of some of the isoquinoline derivatives involved alkylation of the parent base; 3-metylisoquinoline can be substituted either at the methyl group, upon reaction with aromatic nitriles or at C-4, using alkyl halides.
