P tosyl chloride

Matsuura and co-workers (756) have reexamined the reactions of the A -oxides of 2,5-dimethylpyrazine and found that 2,5-dimethylpyrazine di-A -oxide (29) when heated with phosphoryl chloride at 160° gave 2,5-dichloro-3,6-dimethylpyrazine (6%) (30), 3-chloro-2,5-dimethylpyrazine 1-oxide (5%) (31), and 5-chloromethyl-2-methylpyrazine 1 -oxide (9%) (32). In addition small amounts of other chlorinated products, 3-chloro-2-chloromethyl-5-methylpyrazine (33) and 2,5-bischloromethyl-pyrazine (34), were identified. These authors also examined the action of p-tosyl chloride, methane sulfonyl chloride, and mixtures of phosphoryl chloride and concentrated sulfuric acid, but state that these did not give good results. Pyrazine 1-oxide and phosphoryl chloride have been shown to give 2reaction conditions it gave 2-chloropyrazine 1-oxide (757). Pyrazine 1,4-dioxide and benzenesulfonyl chloride also gave a low yield of 2-chloropyrazine 1-oxide (758). 

Kogay has added many other, somewhat more complicated reagents to the conjoining bond, e.g. diethyl malonate, p-toluenesulfonamide, and aniline benzenesulfonyl chloride and p-tosyl chloride pyridine and iodine afford addition of iodine and a pyridinium iodide group to the bond , mercuric acetate in ethanol in the presence of chloride ion affords addition of HgCl and an ethoxy group. A recent review includes a discussion of the reactions of 1,3-dehydroadamantane . 

Step-1. The cis-5-hydroxy-2-propyl cyclopentane on being treated with p-tosyl chloride ii.e., p-toluene sulphonyl chloride) in the presence of dry pyridine yields the corresponding cis-tosyl derivative. 

Toluenesulfonyl chloride Toluene-4-sulfonyl chloride 4-Toluolsulfonyl chloride Tosyl chloride p-Tosyl chloride... 

Acidic reagents seem to offer milder conditions. Dehydration reactions forming cyanides can be performed with phosgene [1049-1052], diphosgene [1053-1055], triphosgene [1056], phenyl chloroformate [1057], oxalyl chloride [1058, 1059], tri-chloroacetyl chloride [1060-1062], acetic anhydride [1063-1074], TFAA [1075-1082], phosphorus oxides [1083-1088], phosphorus oxychloride [1089-1098], phosphorus pentachloride [1099], triphenylphosphine/haloalkanes [1100-1103], thionyl chloride [1104-1118], p-tosyl chloride [1119-1124], triflic anhydride [1125-1127], chlorosulfonyl isocyanate [1128], the Burgess reagent [1129], phenyl chloro-thionoformate [1130], cyanuric chloride [1131-1134], carbodiimides [1135, 1136], CDC [1137], PyBOP [1138], AlCU/Nal [1139], and acetonitrile/aldehyde [1140], and by pyrolysis [1141]. 

Typical procedure. l,4-Dimethyl-5,6-diphenyl-3-propionylbicYclo[2.2. l]hepta-2,5-diene-2-carbonitrile 1474 [1119] A solution of the amide 1473 (104.8 mg, 0.28 mmol) and p-tosyl chloride (119.8 mg, 0.63 mmol) in absolute pyridine (2 mL) was refluxed for 2.5 h. The mixture was then poured onto ice, acidified with 10% aq. HCl, and extracted with diethyl ether. The combined extracts were washed with 10% HCl and brine, dried, and concentrated to dryness. Chromatography on silica gel eluting... 

According to the p-tosyl chloride method, chiral intermediates bearing cyano groups 1478 (R = H, Me) are prepared from amino acid starting materials 1476. 

General procedure. (4R)-N-Benzyloxycarbonyl-4-cyano-2,2-dimethyl- l,3-oxazolidine and (4R,5R)-N-Benz lox carbonyi-4-cyano-2,2-dimethyl-5-methyl-l,3-oxazolidine 1478 [1120] A solution of the amide 1477 (36 mmol), p-tosyl chloride (10.29 g, 54 mmol), and pyridine (70 mL) was purged with Ar and stirred at 80 °C for 1 h. The cmde mixture was then concentrated under reduced pressure and diluted with EtOAc (200 mL). The organic phase was washed with 2 n Hd (3 x 50 mL), water (3 x 50 mL), and saturated NaHCOs solution (3 x 50 mL), dried (Na2S04), concentrated, and purified by flash chromatography (dichloromethane/hexane, 1 1) yield 70-88% of 1478. 

Dimethylazulene-4-carbonitrile 1481 has been prepared from the corresponding carbaldoxime 1480 by dehydration with p-tosyl chloride in 77% yield [1122]. 

Typical procedure. 6,8-Dimethylazulene-4-carbonitrile 1481 [1122] A mixture of 1480 (996 mg, 5.0 mmol) and p-tosyl chloride (955 mg, 5.0 mmol) in dry piperidine (50 mL) was heated under reflux for 8 h. After evaporating the piperidine in vacuo,... 

A key intermediate in a vitamin Bn synthesis, methyl (S)-4-cyano-5,5-dimethyl-6-heptynoate [1123], and a 6-cyano-lH-pyrano[2,3<]pyrazol-4-one derivative [1124] have both been prepared from their carbaldoximes by dehydration with p-tosyl chloride in yields of 88% and 91%, respectively. 

A total synthesis of the sesquiterpenoids (-)-axamide-4 1663 and (—)-axisonitrile-4 1664, affording both natural products, has been accomplished in eleven steps [1233]. From the view of a chemist, it is remarkable that both the isocyanide and its chemical precursor molecule formamide are naturally occurring. The transformation of (—)-axamide-4 into (—)-axisonitrile-4 is carried out with p-tosyl chloride in 94% yield. 

Typical procedure. dl-Axisonitrile-4 1664 [1234] To a solution of dl-axamide-4 1663 (344 mg, 1.39 mmol) in dry pyridine (5 mL), p-tosyl chloride (535 mg, 2.8 mmol) was added at room temperature. The mixture was stirred at room temperature for 15 h, then cooled to 0 °C and crushed ice (3 g) was added. The resulting mixture was stirred at 0 °C for 30 min, diluted with petroleum ether/diethyl ether, (1 1 50 mL), and washed with brine (3 x 10 mL). The combined aqueous layers were extracted with petroleum ether (3 x 15 mL), and the combined organic layers were dried (Na2S04) and concentrated in vacuo. The residue was chromatographed on 30 g of silica gel (eluting with petroleum ether, bp 35-60 °C) to give 0.32 g (100%) of dl-axisonitrile-4 1664 as a pale-yellow solid mp 61-63 °C. 

A synthesis of 17p-amino-5oi-androstan-3ot-ol from epiandrosterone has been performed [1236]. The intermediate 17y6-isocyano-5a-androstan-3j8-ol was formed from the corresponding formamide by dehydration with p-tosyl chloride [1236]. 

Reviews on the synthesis and chemistry of carbodiimides are given in [1248-1250]. Carbodiimides are mainly synthesized in one of three ways from ureas or thioureas, from isocyanates, or from isocyanides. Several reagents have been employed in carbodiimide synthesis phosgene [1252, 1253], dimethylphosgenimi-nium chloride [1254], tiiphosgene [561, 562], phosphorus pentoxide [1255], phos-phoryl chloride [1256], triphenylphosphine dibromide [758, 1257-1261], triphenylphosphine/tetrahalomethanes [1262, 1263], iminophosphoranes [1264-1277], Mitsunobu reagent [1278, 1279], p-tosyl chloride [1280, 1281], and CDC [1137] oxidative additions have also been used [1282-1284]. 

A method has been described for the preparation of carbodiimides 1699 by dehydration of ureas 1696 with p-tosyl chloride under solid-liquid phase-transfer catalytic (PTC) conditions using solid potassium carbonate as a base and a lipophilic quaternary ammonium salt as a catalyst. The method is generally applicable for the synthesis of disubstituted carbodiimides, but is especially useful for un-symmetrically substituted carbodiimides. Yields of the resulting carbodiimides 1699 vary depending on the solvent (usually used at reflux temperature) in benzene or toluene yields of 66-98% are achieved, while in chloroform they are only 30-50% [1281]. 

Types of reaction C-P bond formation Reaction conditions Dichloromethane, room temperature Synthetic strategy Hydrophosphorylation of imines Catalyst p-Tosyl chloride (p-TsCl)... 

Recently, the synthesis of the heptasilylated p-cyclodextrin 4 has been reported [4]. This compound, which is soluble in organic solvents, can be monotosylated at the secondary side in 30 % yield by reaction with one equivalent of NaH in tetrahydrofuran and treatment with p-tosyl chloride (Scheme 1). Subsequent epoxidation and ringopening with UN3 afforded in good yield the monoazide 5, which, after reduction, can be used in coupling reactions with other building blocks [5]. 

I. 78 mmol) was placed in an oven-dried round-bottom flask equipped with Claisen adapter and a stir bar, and the flask was flushed with Ar. Anhydrous pyridine (13 mL) was added and the solution was cooled to —2°C. p-Tosyl chloride (1.013 g, 5.34 mmol) was added over 30 min and the solution was stirred at —4°C for 24 h, then allowed to warm to room temperature. Et20 (90 mL) was added and the solution was transferred to a separatory funnel followed by the addition of 120 mL of H2O and 70 mL of dilute H2SO4 (15 mL concentrated H2SO4 in 180 mL of H2O). The solution was shaken, the aqueous layer was removed, and another 70 mL of H2SO4 solution was added. The aqueous layer was removed and the organic layer was... 

Nair RP, Kim TH, Frost BJ (2009) Atom transfer radical addition reactions of CCI4, CHCI3, and p-tosyl chloride catalyzed by Cp Ru(PPh3)(PR3)Cl complexes. Organometallics 28 4681 688... 

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