Arylethanals reaction

Thus the Meerwein reaction is a homologation of the Sandmeyer reaction. The arylethane radical 10.17 is a homologue of the aryl radical in the Sandmeyer reaction. 

The low yields of vinyl polymers (Ganushchak et al., 1972) are probably due to the arylethane radical 10.17 reacting more rapidly with CuCl2 than with the vinyl monomer. The formation of 10.17 is also the initiation of the polymerization chain reaction. 

Oxidative C-H amination has been an area of intensive research since the publication of CHEC-II(1996). This methodology has been applied to the synthesis of a variety of 1,2-thiazine 1,1-dioxides. In the simple cases, substrates containing an aromatic C-H can be cyclized in the presence of hypervalent iodine. For instance, the reaction of A-methoxy(2-arylethane)sulfonamide 202 with [hydroxyl(tosyloxy)iodo]benzene rapidly affords benzenesulfon-amide 203 in excellent yield (Equation 30) <20030BC1342> see also <2000JOC926> and <2000JOC8391>. 

The cobalt carbonyl complex is also an effective catalyst for the siloxy-methylation of aromatic aldehydes.110 Arylethane-l,2-diol disilylethers are obtained in good yields, resulting from incorporation of one molecule of CO and two molecules of HSiR3. Good selectivity for the siloxymethylation product is observed at 0°C in hexane. At 15°C, faster reaction rates are observed, but the selectivity for the CO-incorporated product is lower. In contrast, aliphatic aldehydes react under these conditions (1 atm CO, 0°C) to give only a small amount of CO-incorporated product, with a major product resulting from hydrosilylation. 

Styrene oxides can be reduced selectively to either 2-arylethanols or 1-arylethan-ols. Attack of hydride at the non-benzylic carbon atom can sometimes be achieved with LiAlH4, but most reducing agents, in particular under acidic reaction conditions, will lead to cleavage of the benzylic C-O bond (Scheme 4.62). 

The reaction of sodium azide with l-bromo-l-nitro-2-arylethenes takes place by a formal 1,3-cycloaddition Scheme leading to 4(5)-aryl-5(4)-nitro-l,2,3-triazoles [487-489], During the synthesis of nitrotriazoles the bromonitroarylethenes can be replaced successfully by the more readily obtainable l,2-dibromo-l-nitro-2-arylethanes [489], The intermediate product in the synthesis of 3-nitropyrazoles from 2,2-dinitroethanol and diazo ketones or diazoacetic ester is 1,1-dinitroethene [490,491] (Scheme 68). 

With styrenes, the typical reaction conditions provide the a-amino P-hydroxy a-arylethanes as the major product. This regioselectivity can be changed by the use of a pH-controlled method when a carbamate is the nitrogen nucleophile [361],... 

Decarbonylation and carbonylation. 1,1 -Di arylethanes (of particular interest are the chiral members) are obtained from decarbonylation of 3,3-diarylpropanals. Such compounds are accessible from cinnamaldehydes in two steps, involving two different Rh-catalyzed reactions. ... 

Acid treatment of arylethanals may lead to 2-phenylnaphthalenes or l,2,9,10-tetrahydro-l,9-epoxydibenzo[a,e]cyclooctenes (Kagan s ether). 2-Phenylnaphthalenes were obtained by a C-condensation of the enolated form on the keto form. The resulting aldol condensation product underwent an intramolecular reaction to give, after rearomatisation, the 2-phenylnaphthalenes, Fig. (1). 

Andersson, C.-M., Larsson, J. and Hallberg, A. (1990) Chelation-controlled, paUadium-catalyzed vinylic substitution reactions of vinyl ethers. 2-Arylethanal equivalents from aryl halides. J. Org. Chem., 55, 5757-61. 

Diphenylethanes (57) are used in industry as heat media and condenser oil, and can be prepared by Friedel-Crafts reaction between a 1-chloro-l-arylethane and an aromatic hydrocarbon in the presence of an MX catalyst (Eq. (26a)). An alternative route is the addition of the styryl cation to an aromatic hydrocarbon (Eq. (26b)). This reaction may be advantageous over the above Friedel-Crafts process in view of the better availability of the starting material (styrene) a disadvantage is that styrene oligomers are usually obtained as by-products. 

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