Pyridine-thiones

Pyridinethiones acylation, 2, 357 alkylation, 2, 357 aromaticity, 2, 148 protonation, 2, 357 tautomerism, 2, 356 Pyridine-2-thiones aromaticity, 2, 156 basicity, 2, 157 oxidation, 2, 357 N-oxide, sodium salt biocide, 1, 399 synthesis, 2, 360... 

Cyclocondensation of pyridine-2-thione 100 with cinnamonitriles 101 in the presence of a catalytic amount of NEts afforded 4,6-dihydropyrido[2,l-Z)][l,3]thiazine-6-ones 102 (98MI10, 99MI26). 

Carboxylic acid esters of thiols are considerably more reactive as acylating reagents than the esters of alcohols. Particularly reactive are esters of pyridine-2-thiol because there is an additional driving force in the formation of the more stable pyridine-2-thione tautomer. 

To release the pyridine-2-thione leaving group and form the free sulfhydryl, add DTT at a concentration of 0.5 mg DTT per mg of modified protein. A stock solution of DTT may be prepared to make it easier to add it to a small amount of protein solution. In this case, dissolve 20mg of DTT per ml of 0.1M sodium acetate, 0.1M NaCl, pH 4.5. Add 25 pi of this solution per mg of modified protein. Release of pyridine-2-thione can be followed by its characteristic absorbance at 343 nm (s = 8.08 X 103M 1cm 1). 

Reduction of the pyridyl disulfide end after SPDP modification releases the pyridine-2-thione leaving group and generates a terminal—SH group. This procedure allows sulfhydryl-reactive derivatives such as maleimide-activated enzymes (Chapter 26, Section 2.3) to be conjugated with DNA probes for use in hybridization assays (Malcolm and Nicolas, 1984). 

N-(10-Undecenoyloxy)pyridine-2-thione (3). To an oven-dried, one-necked, 250-mL, round-bottomed flask equipped with a nitrogen inlet with gas bubbler, a magnetic stirrer, and a dropping funnel are added 3.61 g (28.4 mmol) of N-hydroxythiopyridone (2) (Note 1), 6.20 g (30.0 mmol) of dicyclohexylcarbodiimide... 

Attaching cyclic, bidentate 1-hydroxy-177-pyridin-2-thione, 1-hydroxy-177-pyridin-2-one (1,2-HOPO) and 2-hydroxy-277-isoquinolin-l-one (1,2-HOIQO) ligating units via their C-6 carbon to TREN template produced 19 , 20 and 21 , respectively. 

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