Phosphorus oxychloride , reaction

Phosphorus oxychloride, reaction with dimethy Iformamide and cyclo hexanone, 46,18... 

Title compounds 979 were prepared (75ZC219) by cyclizing 978, prepared by hydrolysis of 977, with phosphorus oxychloride. Reaction of 979 with isobutylamine gave triazolo[5,l-c]triazine 980 (Scheme 181). 

The starting material (48-1) for a pyrrazolopyridazine can be obtained by treating the corresponding enol, which is simply the condensation product of methylmaleic anhydride and hydrazine, with phosphorus oxychloride. Reaction with piperazine leads to the displacement of the sterically more accessible chlorine to afford the alkylation product (48-2). Treatment with hydrazine leads to the replacement of the remaining halogen and the formation of (48-3). The missing carbon is, in this case, supplied by formamide to afford zindotrine (48-4) [51], a compound that shows activity as a bronchodilator. 

Thiocoumarin reacts with phenylmagnesium bromide to give a mixture of 2-phenyl-A -thiochromene and thioflavone, the latter product being presumed to arise by oxidation of 4-hydroxy-2-phenyl-A -chromene, formed via a thiopyrylium cation. 4-Hydroxythiocoumarin has been acetylated at the 3-position, by treatment with acetic acid and phosphorus oxychloride reactions of the product with amines and with phenylhydrazine have been studied. ... 

Assemble in a fume-cupboard the apparatus shown in Fig. 67(A). Place 15 g. of 3,5-dinitrobenzoic acid and 17 g. of phosphorus pentachloride in the flask C, and heat the mixture in an oil-bath for hours. Then reverse the condenser as shown in Fig. 67(B), but replace the calcium chloride tube by a tube leading to a water-pump, the neck of the reaction-flask C being closed with a rubber stopper. Now distil off the phosphorus oxychloride under reduced pressure by heating the flask C in an oil-bath initially at 25-30, increasing this temperature ultimately to 110°. Then cool the flask, when the crude 3,5-dinitro-benzoyl chloride will solidify to a brown crystalline mass. Yield, 16 g., i.e,y almost theoretical. Recrystallise from caibon tetrachloride. The chloride is obtained as colourless crystals, m.p. 66-68°, Yield, 13 g Further recrystallisation of small quantities can be performed using petrol (b.p. 40-60°). The chloride is stable almost indefinitely if kept in a calcium chloride desiccator. 

Method 2. Mix 1 0 g. of 3 5-dinitrobenzoic acid with 1 5 g. of phosphorus pentachloride in a small, dry test-tube. Warm the mixture gently over a small smoky fiame to start the reaction when the reaction has subsided (but not before), boil for 1-2 minutes or until the solid matter has dissolved. Pour the mixture while still liquid on a dry watch glass (CAUTION the fumes are irritating to the eyes). When the product has solidified, remove the liquid by-product (phosphorus oxychloride) by transferring the pasty mixture to a pad of several thicknesses of filter paper or to a small piece of porous tile. Spread the material until the liquid has been absorbed and the residual solid is dry. Transfer the 3 5 dinitrobenzoyl chloride to a test-tube, add 0-5-1 ml. of the alcohol, and continue as in Method 1. 

Very pure acid chlorides may be obtained by reaction between the anhydrous sodium salt of the acid and phosphorus oxychloride, for example ... 

The phosphorus oxychloride formed in the reaction is a dehydrating agent also. 

The preparation of 4-methylcoumarin is an example of the Pechmann reaction, which consists in the interaction of a phenol with a 3-ketonic ester In the presence of a condensing agent (sulphuric acid, aluminium chloride, phosphorus oxychloride or pho.sphoric oxide) ... 

The reaction is again most successful with phenol and indole derivatives. Reaction con-litions are also quite mild. Phosphorus oxychloride may be used in refluxing chloroform or ligher boiling hydrocarbons. Duration of the reaction is usually less than 6 hours (T. Kameta-li, 1977 A E.E. van Tamelen, 1969). 

Carboxylic acid derivatives on pyridopyrimidine rings appear to undergo normal reactions with electrophilic reagents, e.g. the 6-amide (70) is dehydrated to the 6-nitrile with phosphorus oxychloride. 

Benzimidazole 3-oxides, e.g. (189), react with phosphorus oxychloride or sulfuryl chloride to form the corresponding 2-chlorobenzimidazoles. The reaction sequence involves first formation of a nucleophilic complex (190), then attack of chloride ions on the complex, followed by rearomatization involving loss of the fV-oxide oxygen (191 -> 192). 

Kost et al. have studied related reactions of 2-acyl-1-phenylpyrazolidines (422) and l-phenyl-2-thiocarbamoylpyrazolidines (423). The former are converted on reaction with phosphorus oxychloride into tetrahydropyrimido[l,2-a]indoles (424) (72CHE57) and the latter into tetrahydropyrimido[2,l-f ]benzothiazoles (425) under the influence of acidic agents (80CHE169). 

Pyran-2-one, 5,6-dibromo-5,6-dihydro-reactions, 3, 735 Pyran-2-one, 5,6-dihydro-allylic bromination, 3, 799 dehydrogenation, 3, 724, 799 H NMR,3, 581 synthesis, 3, 841, 843 Pyran-2-one, 4,6-dimethyl-irradiation, 3, 677 photochemistry, 3, 678 Pyran-2-one, 5,6-dimethyl-chloromethylation, 3, 680 conformation, 3, 631 Pyran-2-one, 5-f ormyl-IR Spectra, 3, 595 Pyran-2-one, 6-formyl-IR spectra, 3, 595 Pyran-2-one, 5-halo-synthesis, 3, 799 Pyran-2-one, 3-hydroxy-IR spectra, 3, 595 Pyran-2-one, 4-hydroxy-methylation, 2, 57 3, 676 pyran-4-one synthesis from, 3, 816 reactions with phosphorus oxychloride, 2, 57 synthesis, 3, 792, 794, 795, 798 tautomerism, 2, 56 3, 642 Pyran-2-one, 4-hydroxy-6-methyl-methylation, 3, 692 reactions... 

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