Pyridines pyridyl-2-sulfonates

The fallacy of the conception of a multiple-inhibitor molecule is well shown by the compound which Mcllwain (234) made to illustrate this point, namely the hybrid molecule pyridine-3-sulfon-(2-pyridyl) amide, which is the sulfapyridine type analog of pyridine-3-sulfonic acid. Thus it contains the 2-pyridyl substituent in the sulfonamide group which, as shown above, has some inhibitory effect against nicotinamide-stimulated... 

The 5-position is the preferred site for sulfonation (58. 392). This position is more reactive than any of the pyridine ring in. V-[pyridyl-(2)]-thiazolyl-(2)-amine (178) (132, 382, 383). 

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>. 

FIGURE 9.1. Repeat units of the pyridine-containing polymers and other polymers used in the study (a) poly(p-pyridine) (PPy) (b) poly(/ -pyridyl vinylene) (PPPyV) (c) copolymer of PPY and PPyV [PPyVP(R)2V] (d) wrapped copolymer of pyridylvinylene and penylenevinylene ( PPyVPV) (e) wrapped copolymer of dithienylene and phenylene ( PTP) (f) emeraldine base (EB) form of polyaniline (g) sulfonated polyaniline (SPAN). 

Reaction of the two sulfones 2 and 3 with each other in the presence of base resulted in formation of l,2,3-tri(4-pyridyl)cyclopropene. The corresponding 3-benzcnesulfonyl derivative was obtained upon reaction of 4-(dichloromethyl)pyridine with the sulfone 3 under the same conditions. 

Klemm and Merrill88 later devised a method for the preparation of the sulfones of thienof2,3-6]-, -[3,2-6 -, and - 2,3-c]pyridines by reaction of the parent heterocycle with sodium hypochlorite and dilute hydrochloric acid. Thienol2,3-6Ipyridine sulfone (68) behaved as a dienophile toward anthracene, naphthacene, and furan and yielded 8-(3-pyridyl)quinoline on heating Klemm proposes the mechanism of Scheme 19 for this interesting reaction. 

Metal-acid solutions have been employed in the reduction of nitropyridines to aminopyridines. Zinc dust and acetic acid have been used in the preparation of 3-amino-l-benzyl-4-pyridone or 3-amino-l-benzyl-S-iodo-4-pyridone from the corresponding 3-nitro derivatives. Tin or iron in acids is more popular. For example, 3-amino-2-(o-bromobenzyloxy)-pyridine is obtained by the reduction of 2-(o-bromobenzyloxy)-3-nitropyridine using iron and hydrochloric acid. Various ferrous salts have also been effective reducing agents. Several derivatives of phenyl 5-amino-2-pyridyl sulfide (K-16) (or the sulfone)are... 

Whereas the previous arene electrophilic substitutions take place at ortho position of pyridine coordinating group, the sulfonation with arylsulfonyl chloride of phenylpyridines but in the presence of a ruthenium(II) catalyst [RuCl2(p-cymene)]2 surprisingly led Frost et al. to observe for the first time an unexpected regioselective sulfonation at weto-position of the directing 2-pyridyl group [(Eq. 49)] [111]. 

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