Phosphorus pentachloride with amides

By treatment of this oxime with phosphorus pentachloride or thionyl fhloride in ether solution, smooth conversion into benzanilide, m.p. 163°, results. The change of any oxime into a substituted amide under the conditions mentioned is usually termed the Beckmann rearrangement. The above example may be represented ... 

The method described is a modification of the procedure used by Ghosez to synthesize cinnamonitrile. 3-(2-Furyl)acrylo-nitrile has been prepared by catalytic condensation of furfural with acetonitrile in the vapor phase at 320°, by dehydration of the corresponding amide over phosphorus pentachloride, and by decarboxylation of 3-(2-furyl)-2-cyanoacrylic acid. ... 

Thus, depending on the conditions, the reaction of methylpyrazolylketones with phosphorus pentachloride leads to products from substitution of the carbonyl oxygen by chlorine, o, /3-dichlorovinylpyrazoles, that can be dehydrohalo-genated with sodium amide to ethynylpyrazoles or to Q ,/3-dichloroethylenes. The... 

Oxo-4,5-dihydro-l//-l,2,4-benzotriazepine-3-carboxylates8can be transformed into the acid chlorides 10 with phosphorus pentachloride and the crude products converted into various amides and esters 11 by treatment with amines and alcohols, respectively. Selected examples are given.347... 

A classical procedure for the synthesis of the A-(1-chloroalkyl)amides1 or carbamates68 involves substitution of the hydroxy group in stable A-( 1-hydroxyalkyl)amides (or carbamates) by a halogen function with reagents such as thionyl chloride, phosphorus pentachloride, phosphorus pentabromide, etc. In certain cases merely heating in concentrated hydrochloric or hydrobromic acid suffices1. 

The traditional method for transforming carboxylic acids into reactive acylating agents capable of converting alcohols to esters or amines to amides is by formation of the acyl chloride. Molecules devoid of acid-sensitive functional groups can be converted to acyl chlorides with thionyl chloride or phosphorus pentachloride. When milder conditions are necessary, the reaction of the acid or its sodium salt with oxalyl chloride provides the acyl chloride. When a salt is used, the reaction solution remains essentially neutral. 

One hundred and fifty grams (1.8 moles) of pure cyanoacet-amide (Org. Syn 9, 36) is thoroughly mixed in a large (20-cm.) mortar with 150 g. (0.7 mole) of phosphorus pentachloride (Notes 1, 2 and 3). This mixture is transferred (Note 4) as quickly as possible to a 500-cc. Claisen flask equipped with a 360° thermometer and an air-intake tube (Note 5). The Claisen is connected by means of a double-length air condenser to a 250-cc. filter flask which in turn is connected to a water pump (Note 6) through a manometer. 

Phosphorus pentachloride (101) chlorinates amides, and the products (115) can be reductively dehalogenated with sodium borohydride, thus providing a two-step... 

Beckmann rearrangement org chem An intramolecular change of a ketoxime into its isomeric amide when treated with phosphorus pentachloride. bek-man re-g ranj-mont ... 

The 2-aminoquinazolines 259 were prepared in two independent ways. The 2-quinazolinone 258 was transformed to 2-aminoquinazoline 259 by treatment with phosphorus oxychloride and subsequently with sodium amide in liquid ammonia, or with phosphorus pentachloride under carefully controlled conditions [75JCS(P1)1471]. Attempts to prepare the N-substituted derivatives failed, but the reaction was successful with the unsubstituted cis cyclopentane-fused homolog [76JCS(P1)1415]. 

Racemic 2-ethylhexanonitrile has been obtained only by the action of phosphorus pentachloride on 2-ethylhexanaldoxime 4 the levorotatory form has been prepared from the active amide by the method described.6 Other amides have been converted to nitriles by dehydration with thionyl chloride.6-6... 

This method has been used extensively for the generation of diene- and triene-conjugated nitrile ylides (see Section 7.4.1.2) using strong bases. Potasium tert-butoxide (58) was used for the most part but in recent work (59,60) it was reported that lithium bis(trimethylsilyl)amide is both more effective and more convenient. It has also been shown that thermally unstable imidoyl chlorides for use in these reactions can be prepared by reaction of the corresponding amides with chlorodi-methylformiminium chloride at 0 °C, a reaction that is more effective than using either thionyl chloride or phosphorus pentachloride at higher temperatures (61). 

Xanthone is unreactive towards hydrazine and phenylhydrazine. The oxime is obtained by reaction of xanthione (xanthene-9-thione) with hydroxylamine, or from xanthone and hydroxylamine in pyridine. When the oxime is heated in water with phenylhydrazine, the phenylhydrazone is formed. In acid solution, xanthone reacts normally with 2,4-dinitro-phenylhydrazine but xanthone-1 -carboxylic acid (435) gives the pyridazinone (436), possibly via the hydrazone (57JCS1922). When the oxime is heated with phosphorus pentachloride it undergoes a Beckmann rearrangement to give the amide (437) (70MI22300). 

Conversion of amides into nitriles may be effected by treating them with a variety of dehydrating reagents. Among those that have been employed are phosphorus pentoxide, phosphorus pentachloride,170 ethyl polyphosphate,171... 

Cyclocondensation of the amide (32) with phosphorus pentachloride affords the 1,2-benzoselenazolium salt (19 Scheme 11). Isoselenazolium perchlorates (33) are synthesized as shown in Scheme 12 (76S273). 

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