Ketones aryl-pyridyl

The aryl pyridyl ketone 66 cannot be formed by triazolo ring opening in basic medium. It has been proposed that the cationic intermediate formed in the catalytic cycle is in equilibrium with an azonium form, which with traces of water loses nitrogen, then a probable extrusion of Pd gives an alcohol, which is rapidly oxidized to ketone by air (Scheme 12). 

The reaction tolerates a wide variety of EWG groups (ester, amide, nitrile, ketone, sulphonyl, 2-pyridyl etc), and amines (aliphatic, aryl,... 

Both vinyl- and aryl triflates have been cross-coupled with 2-furylzinc chloride [26-28]. Since vinyl triflates are easily obtained from the corresponding ketones, they are useful substrates in Pd-catalyzed reactions. In the following example, a Negishi coupling of 2-furylzinc chloride and indol-5-yl triflate (22) provided an expeditious entry to 2-(5 -indolyl)furan (23). Protection of the NH in the indole ring was not required. A similar reaction was successful with pyridyl- and quinolinyl triflates. 

Diaryl ketones.2 In the presence of this complex (1 equivalent) S-(2-pyridyl) aryl thioates (1 equivalent), prepared from aryl carboxylic acids, undergo reductive homocoupling to diaryl ketones (equation I). 

A different type of reaction, in which the intermediate formation of a chelate ring is crucial, is the reaction of pyridyl thioates with Grignard reagents, which achieves an overall conversion of an alkyl or aryl halide to a ketone (Scheme 105).378 Grignard reactions are highly susceptible to chelation factors and stereoselectivity is observed in the addition of organomagnesium or... 

Keto-sulfones, which contain a 2-pyridyl ketone moiety, react with alkylidenemalononitriles to afford 2-amino-5-sulfonyl-4-aryl-6-(pyridin-2-yl)-47/-pyran-3-carbonitriles 86 (Equation 47) <1997JOC6575>. Likewise, (3-keto-sulfoxides featuring a 2-pyridyl ketone moiety react with alkylidenemalononitriles to form 2-amino-5-sulfinyl-4-aryl-6-(pyridin-2-yl)-4//-pyran-3-carbonitriles. Additionally, chiral (3-keto-sulfoxides that contain a 2-pyridyl ketone moiety can add to alkylidenemalononitriles with high stereoselectivity <1997JOC6575>. 

The quaternary salts of ketals of 4-pyridyl alkyl and aryl ketones undergo reduction with sodium borohydride to give the expected 1,2,3,6-tetrahydropyridines.47" Reduction of an analogous ketal of a quaternary salt of a 3-pyridyl ketone led to rupture of the ketal ring.476... 

A wide variety of substituents are tolerated. The group R can be alkyl, halogen, alkoxy, -amido, azi-domethyl, ester, aryl, aryloxy and aryloyl, and at least one ortho substituent is permissible with no loss in yield. TTie aromatic ring can also be 2-naphthyl, 9,10-dihydro-2-phenanthryl, 3-pyridyl, thiophen-2-yl or pyrrol-3-yl. The group R can be hydrogen, yl, acyl or acetic acid. Beyond Ae antiinflammatory targets, successful reaction substrates include the methyl ketones of a binaphthyl crown ether, a morphinane and a polyaromatic hydrocarbon. The preparation of ibuprofen methyl ester (38) is shown in equation (37) as a typical example. ... 

Reaction of the l,5-diphenyl-3-(2-pyridyl)pentane-l,5-dione 47 with 2.5equiv of benzylpentacarbonylmanganese in petroleum under reflux gave a small amount of the symmetrical di-aryl-manganated product 48 but mostly the complex 49, which is manganated at only one aryl carbon (by Mn(CO)4) but also (by Mn(CO)3 with N- and O-coordination) at the methylene carbon adjacent to the Mn(CO)4-coordinated ketone carbonyl (Scheme 6). The latter is a rare example of direct cyclomanganation at a saturated carbon and the only known case adjacent to carbonyl <2005JOM3348>. 

Diaryl ketones can also be prepared by coupling aryl iodides with phenylboronic acid (12-28), in the presence of CO and a palladium catalyst.This reaction has been extended to heteroaromatic systems, with the preparation of phenyl 4-pyridyl ketone from phenylboronic acid and 4-iodopyridine. 2-Bromopyridine as coupled with phenylboronic acid, CO and a palladium catalyst to give phenyl... 

PhNCO or CH2=CHC02Me. The reaction of N4S4 with various aryl and alkyl benzyl ketones, oxindole, benzyl a-pyridyl ketone, or a-phenacyl-... 

In practice, the azide decompositions are usually carried out in boiling toluene or xylene and give good yields of 3-alkyl-170,184,187 and 3-aryl-anthranils.185,188 Yields of 3-unsubstituted anthranils from o-azidoben-zaldehydes are generally much lower.170 The method has also been used to prepare 3-(j3-styryl)anthranils (106) from o-azidochalcones,189 3-methyl-naphtho[2,3-c]isoxazoles from 3-acetyl-2-azidonaphthalene,190 and 3-(2-pyridyl)anthranils from o-azidophenyl pyridyl ketones.191 This last reaction is of interest in that 2-(2-azido-3,5-dibromobenzoyl)pyridine in boiling toluene yields almost equal amounts of 5,7-dibromo-3-(2-pyridyl)anthranil (43%) and the zwitterionic pyrido[l,2-f>] cinnolin-6-ium 139 (41%). 

Dehydrogenation of a-pyridinealdehyde hydrazone (251) yields not a-pyridyldiazomethane (252) but the cyclic isomer l,2,3-triazolo[3,4-a]pyridine (253).1 A similar ring closure is observed in diazo group transfers onto alkyl or aryl(2-pyridyl)methyl ketone (254) in MeOH/KOEt.1 The diazo intermediate could not be isolated but 3-acyl[l,2,3]triazolo[3,4-a]pyridine (255) is obtained.1... 

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