Pyridine 3,5-dichloro

D. T, Burns, K., Titus, D.D., Girard, G.R., Reiff, W.M. and Mascavage, L.M. (2003) Dichloro (pyridine-2-carboxamido-N 1, N2)gold(III), a bis-nitrogen aurocycle syntheses, gold-197 Mossbauer spectroscopy, and X-ray crystal structure. Inorganica Chimica Acta, 346, 1. 

Annibale, G., Canovese, L., Cattalini, L., Marangoni, G., Michelon, G. and Tobe, M.L. (1984) Displacement by chloride of pyridine-2-carboxylate from dichloro (pyridine-2-carboxylato) gold(111) in acidic solution the position of ring opening. Journal of the Chemical Society, Dalton Transactions, (8), 1641. 

Si°-4- ]l-(sc4tonitnle)dichloro(pyridine)pla[irum(II) [5P- l]-facetoiiiinkWk Mao(pyridte>platg nn... 

An interesting transformation involving the indole nucleus was found from propargylic carboxylates to give tetracychc compounds with Au(I) (equation 85). This reaction proceeds by an allene-gold complex in equilibrium with the aUcenyl-gold species, which reacts intramolecularly with the indole to form the product. When the reaction of these substrates is performed with dichloro(pyridine-2-carboxylato)gold(III) or Pt(II) as catalysts, products in equation (86) are obtained instead. This new reactivity can be explained by a formal [3 + 2] cycloaddition of 1,3-dipole... 

Scheme X.12. The hydroxylation of 5a-cholestan-3-one by 2,6-dichloro-pyridine N-oxide catalyzed with ruthenium porphyrin.

C1iHioCl2CoNh, Dichloro(pyridine-2-aldehyde 2-pyridylhydrazone)co-balt(ll), 31B, 425... 

Dichlorobutane. Place 22-5g. of redistilled 1 4-butanediol and 3 ml. of dry pyridine in a 500 ml. three necked flask fitted with a reflux condenser, mechanical stirrer and thermometer. Immerse the flask in an ice bath. Add 116 g. (71 ml.) of redistilled thionyl chloride dropwise fix>m a dropping funnel (inserted into the top of the condenser) to the vigorously stirred mixture at such a rate that the temperature remains at 5-10°. When the addition is complete, remove the ice bath, keep the mixture overnight, and then reflux for 3 hours. Cool, add ice water cautiously and extract with ether. Wash the ethereal extract successively with 10 per cent sodium bicarbonate solution and water, dry with anhydrous magnesium sulphate and distil. Collect the 1 4-dichloro-butane at 55-5-56-5°/14 mm. the yield is 35 g. The b.p. under atmospheric pressure is 154 155°. 

The reactivity of the amino radical has not yet been investigated. Alkaline hypochlorite oxidation, known in the pyridine series to yield azo derivatives (155,156). and photolysis of N,N-dichloro derivatives, which may be obtained by action of sodium hypochlorite on amino derivatives in acidic medium (157). should provide interesting insight on this reactivitv. 

Direct halogenation of sucrose has also been achieved using a combination of DMF—methanesulfonyl chloride (88), sulfuryl chloride—pyridine (89), carbon tetrachloride—triphenylphosphine—pyridine (90), and thionyl chloride—pyridine—1,1,2-trichloroethane (91). Treatment of sucrose with carbon tetrachloride—triphenylphosphine—pyridine at 70°C for 2 h gave 6,6 -dichloro-6,6 -dideoxysucrose in 92% yield. The greater reactivity of the 6 and 6 primary hydroxyl groups has been associated with a bulky halogenating complex formed from triphenylphosphine dihaUde ((CgH )2P=CX2) and pyridine (90). 

Phosphorus pentasulfide in pyridine can be used also for simultaneous substitution of oxygen and chlorine in polysubstituted pyridazinones. For example, 4,5-dichloro- and... 

Pyridin-4-one, 3,5-dichloro-2,6-dimethyl-tautomerism, 2, 111 Pyridin-4-one, 1,4-dihydro-polymers, 1, 297 Pyridin-4-one, 2-dimethylamino-synthesis, 2, 419... 

In this solvent the reaction is catalyzed by small amounts of trimethyl-amine and especially pyridine (cf. 9). The same effect occurs in the reaction of iV -methylaniline with 2-iV -methylanilino-4,6-dichloro-s-triazine. In benzene solution, the amine hydrochloride is so insoluble that the reaction could be followed by recovery. of the salt. However, this precluded study mider Bitter and Zollinger s conditions of catalysis by strong mineral acids in the sense of Banks (acid-base pre-equilibrium in solution). Instead, a new catalytic effect was revealed when the influence of organic acids was tested. This was assumed to depend on the bifunctional character of these catalysts, which act as both a proton donor and an acceptor in the transition state. In striking agreement with this conclusion, a-pyridone is very reactive and o-nitrophenol is not. Furthermore, since neither y-pyridone nor -nitrophenol are active, the structure of the catalyst must meet the conformational requirements for a cyclic transition state. Probably a concerted process involving structure 10 in the rate-determining step... 

Reagent P-K a 2-Chloro- pyrimidine 2-Chloro- 3-nitro- pyridine 2-Chloro- 5-nitro- pyridine 2,4-Dichloro- phenylamino-s-triazine ... 

Tlie betaine 24, obtained from the reaction of 2,3-dichloro-l,4-naphthoquinone with a pyridine/water mixture, reacts with CI2 to form A-(l-... 

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