Pentachloride carbonyls

Hydroxylamine Barium oxide and peroxide, carbonyls, chlorine, copper(II) sulfate, dichromates, lead dioxide, phosphorus trichloride and pentachloride, permanganates, pyridine, sodium, zinc... 

Conversion of a carbonyl to a gem-dichloro roup is carried out with phosphorus pentachloride [67, 6S] (equations 51 and 52). Under these conditions, 1,4-dicatbonyl compounds give cyclic ethers [67] (equation 53). 

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... 

MRH Bromine 1.21/91, carbon tetrachloride 2.89/83, chlorine 3.85/82 Silane burns in contact with bromine, chlorine or covalent chlorides (carbonyl chloride, antimony pentachloride, tin(IV) chloride, etc.) [1], Extreme caution is necessary when handling silane in systems with halogenated compounds, as a trace of free halogen may cause violent explosions [2],... 

The treatment of l-pyrrolylmethylenemalonic acid (118) with phosphorus pentachloride in methylenechloride at ambient temperature gave 1-oxo-l//-pyrrolizine-2-carbonyl chloride (1383) in 42% yield (82CB706). 

Most reactions of oxadiazolinones (62) involve nucleophilic attack at the carbonyl group. This is typically followed by opening of the ring, often with subsequent rccyclization to a different heterocycle. Simple nucleophilic displacement occurred on conversion of oxadiazolinone (62a R = R) into chloro-oxadiazole (63) on treatment with a mixture of phosphorus oxychloride and phosphorus pentachloride <84JIC436) or with thionyl chloride <90AP(323)595>. 

The preparation of chromone-2-carbonyl chlorides from the acid and thionyl chloride often leads to the trichloride (498) as a byproduct (61JGU523) but this is suppressed when a few drops of DMF are added (72JMC865) or phosphorus pentachloride and cyclohexane are used (73BSF2392). When the trichloride is treated with water, an amine or acid, it rearranges to 4-chlorocoumarin (499) (63JGU1806). 

Tetrahydropyran-4-ones, for example diethyl 6-methyl-4-oxotetrahydropyran-3,3-dicar-boxylate (600), are brominated at C-3 (77JCS(Pl)l647). Chromanones are readily halogenated at C-3 (see above) when they are treated with phosphorus pentachloride, the reaction does not stop at monochlorination the carbonyl group is attacked and 3,4-dichloro-2//-chromene (601) is formed, an uncommon conversion of a chromanone into a chromene (79TL3901). Chroman yields 4- and 6-bromides when treated with NBS-benzoyl peroxide. 

VI, obtained from stereospecific reactions of the corresponding optically active alcohol (11) with thionyl chloride, phosphorus pentachloride, etc., was not racemized under any of the reaction conditions. Monitoring the carbonyl absorption frequencies in the IR during these decarbonylations showed that the transformations II — III — IV took place during the conversion of V to racemic VI. Thus rearrangement or decomposition or both could be responsible for the racemization. 

Replacement of the carbonyl function by two chlorines occurs with phosphorus pentachloride in ether ... 

Exercise 16-31 Work out reasonable mechanisms for the reactions of phosphorus pentachloride and sulfur tetrafluoride with carbonyl groups. Both phosphorus and sulfur can accommodate five or more) bonded atoms, and the structure of phosphorus pentachloride in the solid state is [PCI4 ] [PCl60]. 

Pyrrolo-thiazepine 236 was obtained by connecting the a-carbon of the pyrrole moiety with the carbonyl group of 237 using phosphorus pentachloride in anhydrous dichloromethane (Equation 20) <2003MOL678>. A similar procedure was followed by Campiani et al. <1997EJM241>. Petrova et al. reported the synthesis of the related imidazothiazepine by polyphosphoric acid-mediated cyclization <2003SC4355>. 

One of the earliest attempts to prepare analogues of FA as potential inhibitors involved the synthesis of 2-amino-4,7-dihydroxypteridine-6-carboxylyl-p-ami-nobenzoic acid (612) (in which the change from the structure of FA itself is exchange of the methylene bridge for a carbonyl group, and oxidation of position 7 to a lactam). This compound, which was a surprisingly effective inhibitor, was prepared from isoxanthopterin carboxylic acid (611) by in situ conversion to its acid chloride with a mixture of phosphorus oxychloride and phosphorus pentachloride, followed by addition of p-aminobenzoylglutamic acid (Scheme 3.132) [115]. 

B.13 2. B.14 3. A.01 3.A.02 3.A.03 3.A.04 3.B.05 3.B.06 3.B.07 3.A.08 3.A.09 3.A.10 3.A.11 Bis(2-hydroxyethyl)sulfide 3,3-Dimethyl-2-butanol Carbonyl dichloride Cyanogen chloride Hydrogen cyanide Trichloronitromethane Phosphorous oxychloride Phosphorous trichloride Phosphorous pentachloride Trimethyl phosphate Triethyl phosphate Dimethyl phosphate Diethyl phosphate... 

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