Pyridyl pyridine

Methyl-5-(4-pyridyl)-7-aza- 2-Araino-3-iodo-6-methyl-,S- (4-pyridyl)pyridine Trimethylsilylethyne. Pd(PPh,)jCl4, Cut 96,40 ... 

Pyridinol A -oxide, hi83 Pyridinols, hi79 thru hi81 2(l//)-Pyridone, hl79 2-(2-Pyridyl)pyridine, d790... 

The Pd-catalyzed carbonylation of 2,6-dibromopyridine in the presence of 2-pyridylamine gave N,lV -di(2-pyridyl)pyridine-2,6-dicarboxamide under relatively high pressure and prolonged reaction time [156]. Partial aminocarbonylation of 2,6-dibromopyridine was more cumbersome—only 55% of the monocarboxamide 195 was isolated in a shorter reaction time accompanied by the corresponding 2,6-dicarboxamide in 32% yield. 

The arylborane, or heteroarylborane (8 mmol), TBA-Br (1.28 g, 4 mmol), powdered KOH (11.8 g), the haloarene (12 mmol) and Pd(Ph3P)4 (0.46 g, 0.4 mmol) are refluxed in THF under N2 for 8 h. EtOAc (100 ml) is added to the cooled mixture and the organic mixture is washed with brine (40 ml) and dried (MgS04). Evaporation under reduced pressure and chromatography from silica gives the biaryl system [e.g. 3-(2-pyridyl)pyri-dine, 85% 3-(3-pyridyl)pyridine, 82% 3-(5-methoxycarbonyl-2-pyridyl)pyridine, 63% 3-(6-methoxy-2-pyridyl)pyridine, 77% 3-(2-thienyl)pyridine, 75%]. 

A number of syntheses of substituted 2,3 -bipyridines are worthy of note. Tetracyclone heated at 215°C with nicotinonitrile affords 3,4,5,6-tetraphenyl-2,3 -bipyridine, whereas 3,4-di(2-pyridyl)pyridine is obtained by an oxidative degradation of the corresponding 6,7-disubstituted thiazolo[3,2-a]-pyridinium salt. Nicotinic acid on UV irradiation in aqueous solution at pH 4-6 gives 2,3 -bipyridine-5-carboxylic acid, whereas irradiation of picolinic acid in the same pH range in the absence of metal ions gives some 2,3 -bipyridine. 6,6 -Diphenyl-2,3 -bipyridine is thought to be formed from... 

Steric effects of other substituents such as Et, PhCH2, 2-pyridyl, C02Me, and MeCONH are larger than those five showing the Bronsted correlation. Consequently, they cause lower reactivity. For example, the reactivities of 2-acetylamino- and 2-(2-pyridyl)pyridine are about 10 and 25 times less, respectively, than that suggested by the rate-acidity correlation for the five substrates with an approximately uniform steric impediment.72... 

Nomenclature is always a vexing subject the ligand (Fig. 1) has been known variously as 2,2, 2"-tripyridyl, 2,2, 2"-tripyridine, 2,6 -bis(2-pyridyl)-pyridine, and 2,2 6, 2"-terpyridine. The latter is the systematic name (262) and will be used throughout this article. All other compounds will be named systematically, according to lUPAC recommendation A-54. In this article, the abbreviations terpy, quaterpy, quinquepy, bipy, and phen will be used for the ligands in Figs. 1-5, respectively. Substituted derivatives will not be similarly described thus 4,4"-diethyl-4 -phenyl-2,2 6, 2"-terpyridine (Fig. 6) will be denoted 4,4"-Et2-4 -Phterpy. 

SYNS CYCLOHEXYL 4-PYRIDYLKETONE KETONE, CYCLOHEXYL 4-PYRIDYL PYRIDINE, 4-(CYCLOHEXYLCARBONYL)-... 

SYNS l-HEPTANONE, l-(4-PYRIDYL)- HEPTYL 4-PYRIDYL KETONE KETONE, HEPTYL 4-PYRIDYL PYRIDINE, 4-HEPTANOYL- l-(4-PYRIDYL)-l-HEPTANONE... 

SYNS l-BUTANONE, 1-(4-PYRIDYL)- 4-BUTYRYLPYRIDINE KETONE, PROPYL 4-PYRIDYL PYRIDINE, 4-BUTYRYL- t-(4-PYRIDYL)-l-BUTANONE... 

Using this methodology, the size and shape of the cavity determines which oligomer will be isolated (Scheme 10.7). Indeed, bowl 16 produces dimer 19 whereas the small coordination tube 21, which allows the complexation of only one molecule of the reactant, affords monomer 18, a silanetriol. In this case, starting from 4 equiv of 3,5-bis(3-pyridyl) pyridine 20 and 6 equiv of Pd(en)(N03)2, tube 21 can only be prepared in situ by means... 

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