Aluminum Chloride rearrangements

The structure of celtrobiose was established through its oxidation to celtrobionic acid and subsequent cleavage with N sulfuric acid to d-glucose and n-altronic acid. Since the biose linkage should not be affected by the aluminum chloride rearrangement, celtrobiose was thus proved to be 4-j8-D-glucopyranosido-D-altrose. 

In the synthesis of n-altrose from D-ribose, first effected by Levene and Jacobs, the only crystalline intermediate was the characteristic calcium D-altronate -3.5 H2O. The sirupy lactone prepared from it was then reduced to n-altrose with sodium amalgam, as mentioned earlier in this review. Calcium n-altronate has been obtained from other sources also, such as the aluminum chloride rearrangement of the acetates of lactose, cellobiose and glucose and subsequent transformation of the neolactose, celtrobiose and altrose derivatives thus produced (see Section... 

Studies on the stability of 1,2-dihydro-2,4,6-triphenyl-1,3,5-triazine (369) included its synthesis from the aromatic 1,3,5-triazine 368. However, in the presence of aluminum chloride rearrangement occurs to give a 16% yield of 2,4,5-triphenylimidazole (370). A suggested mechanism proposed that the unstable dihydrotriazine undergoes a radical-induced ring opening and contraction to 370. ... 

Kakac and Hudlicky (3, 46) used infrared absorption to analyze liquid mixtures of halothane and 1-bromo-2-chloro-1,1,2-trifluoroethane resulting from aluminum chloride rearrangement of the latter. Davies et al (47) and Sechzer et al (48) used infrared absorption to analyze for halothane in respiratory gases during and after anesthesia. Rehder et al (27) and Larson et al (49) used commercial infrared halothane analyzers for measuring halothane in gas mixtures. 

Direct alkylation of benzene using 1 chlorobutane and aluminum chloride would yield sec butylbenzene by rearrangement and so could not be used... 

Carbocations usually generated from an alkyl halide and aluminum chloride attack the aromatic ring to yield alkylbenzenes The arene must be at least as reactive as a halobenzene Carbocation rearrangements can occur especially with primary alkyl hal ides... 

Rearrangement is especially prevalent with primary alkyl halides of the type RCH2CH2X and R2CHCH2X Aluminum chloride induces ionization with rearrangement to give a more stable carbocation Benzylic halides and acyl halides do not rearrange... 

The preference for O acylation of phenols arises because these reactions are kmetically controlled O acylation is faster than C acylation The C acyl isomers are more stable how ever and it is known that aluminum chloride is a very effective catalyst for the conversion of aryl esters to aryl ketones This isomerization is called the Fries rearrangement... 

The Eries rearrangement of phenol esters gives a mixture of 2- and 4-acylphenols (56). The reaction is cataly2ed by Lewis acids such as aluminum chloride or by Brmnsted acids like hydrogen fluoride. This reaction is used in the production of 4-hydroxyacetophenone [99-93-4] a raw material for... 

The title compounds also undergo the Claisen rarrangement (5-allyloxypyrazoles 4-allyl-5-pyrazolones) and are readily transformed into 5-chloropyrazoles by means of phosphorus oxychloride (8OCHE1). In the presence of aluminum chloride 5-acyloxypyrazoles (481) undergo the Fries rearrangement affording 4-acyl-5-hydroxypyrazoles (482). 

Fries rearrangement (Section 24.9) Aluminum chloride-promoted rearrangement of an aryl ester to a ring-acylated derivative of phenol. 

Ether groups in the benzene ring of quinazoline behave as in ethers of homocyclic aromatic compounds, e.g., they can be demethylated with anhydrous aluminum chloride. Allyl ethers also undergo a Claisen rearrangement/ ... 

Fries rearrangement org chem The conversion of a phenolic ester into the corresponding 0- and p-hydroxyketone by treatment with catalysts of the type of aluminum chloride. frez re a ranj-mant)... 

Apart from the reaction of cyclohexanecarboxylic acid with methyllithium, cyclohexyl methyl ketone has been prepared by the reaction of cyclohexylmagnesium halides with acetyl chloride or acetic anhydride and by the reaction of methylmagnesium iodide with cyclohexanecarboxylic acid chloride. Other preparative methods include the aluminum chloride-catalyzed acetylation of cyclohexene in the presence of cyclohexane, the oxidation of cyclohexylmethylcarbinol, " the decarboxylation and rearrangement of the glycidic ester derived from cyclohexanone and M)utyl a-chloroj)ropionate, and the catalytic hydrogenation of 1-acetylcycIohexene. "... 

A somewhat similar isomerization was observed with the sultam 5-methylimino-4-phenyl-l,3,4-dithiazolidine 1-dioxide (17 i = H). On heating at 60°C in the presence of benzoyl chloride, rearrangement into the isomeric 5-phenylimino-4-methyl-l,3,4-dithiazolidine 1-dioxide (19, 1 = H) was found (Scheme IV.ll). As intermediate can be proposed the amidinium salt 18 (78JOC4951). Furthermore, NMR-controlled test tube experiments revealed that this rearrangement also occurs under influence of aluminum trichloride and methanesulfonyl chloride. Also, the 2-phenyl derivative 17 (R = CeHs) could be isomerized it required heating in acetone with m-dichlorobenzoic acid as catalyst (Scheme IV.ll). 

Many hydroxy compounds would not survive such harsh treatment therefore other methods must be used. Some alcohols were hydrogenolyzed with chloroalanes generated in situ from lithium aluminum hydride and aluminum chloride, but the reaction gave alkenes as by-products [605], Tertiary alcohols were converted to hydrocarbon on treatment at room temperature with triethyl- or triphenylsilane and trifluoroacetic acid in methylene chloride (yields 41-92%). Rearrangements due to carbonium ion formation occur [343]. 

Structures 2 and 21 can be rearranged under aluminum chloride catalysis, on thermolysis in various solvents, or on dry heating. 

---