Coupling reactions intramolecular

Tb allium (ITT) ttifluoroacetate promotes olefin cyclization reactions and intramolecular coupling reactions (32,33). 

The diazonium salt 2 derived from 2-(3-hydroxyphenoxy)aniline (1) undergoes an intramolecular coupling reaction to yield the dibenzoxadiazepinol 3.153... 

The 1,5- and 1,6-dialdehydes 22 and 24 undergo the annulative pinacol coupling to give the cyclic vzc-diols 23 and 25, respectively (Scheme 13) [29]. The vanadium-catalyzed intramolecular coupling reaction of 1,5-diketone 26 also proceeds with excellent selectivity (Scheme 14) although the intermolecular coupling of ketones such as acetophenone results in low diastereoselectivity under these conditions [21]. 

In contrast to the high regioselectivity and good yields of electroreductive intramolecular coupling reactions of ketones with multiple bonds shown in Schemes 34 to 37, the yields of interm olecular coupling reactions have been very low until recently. However, by using carbon fiber electrodes, intermolecular coupling reactions have... 

Radical anions resulting from cathodic reductions of molecules react with electrophilic centers. As an example (Scheme 8), the reduction of compounds in which a double bond is not conjugated with a carbonyl group, involves an intramolecular coupling reaction of radical anion with alkene [12]. 

Finally, the intramolecular coupling reaction between an olefin and a pyrrole ring has been examined (Scheme 40). In this example, a 66% isolated yield of the six-membered ring product was obtained. A vinyl sulfide moiety was used as the olefin participant and the nitrogen protected as the pivaloyl amide in order to minimize the competition between substrate and product oxidation. Unlike the furan cyclizations, the anodic oxidation of the pyrrole-based substrate led mainly to the desired aromatic product without the need for subsequent treatment with acid. 

Intramolecular coupling reactions between nucleophilic olefins have also proven to hold potential as synthetically useful reactions. The first example of this type of reaction was reported by Shono and coworkers who examined the intramolecular coupling reaction of an enol acetate and a monosubstituted olefin (Scheme 41) [50]. This reaction was conducted in an effort to probe the nature of the radical cation intermediate generated from the anodic oxidation of... 

The intramolecular coupling reaction does not occur when diphenylethylenes, that is, stilbene and its methyl derivatives, are electrolyzed under the same conditions (Stuart and Ohnesorge 1971). This difference in the anodic behavior of these substances was attributed to the low stability of the cation-radicals of stilbene and its methyl derivatives in comparison to the cation-radicals of tetraphenylethylene. The participation of the cation-radicals in the cyclization of tetraphenylethylene has been unequivocally proved (Svanholm et al. 1974, Steckhan 1977). 

Intramolecular coupling reactions could also be performed, as demonstrated by the synthesis of the tetracyclic derivative 558 <2006JOC1969>. 

Intramolecular coupling reactions bear some important advantages namely, the opportunity of directed cross coupling and, in most cases, a reliable regioselectivity by kinetic or thermodynamic control of the atropisomer ratio. 

Presented in this section are only such stereoselective intramolecular coupling reactions in which stereocontrol can be exerted. Coupling reactions like the aporphine ring closure of 2,6,7-trialkyl-l-(3,4-dialkylbenzyl)-l,2,3,4-tetrahydroisoquinoline with vanadium(V) oxytriflu-oride to give l,2,6,10,ll-pentaalkyl-5,6,6a,7-tetrahydro-4/F-naphtho[l,2,3-i/]isoquinoline, will not be dealt with in detail1 2,... 

The well-known and widespread phenolic oxidations3 and the related nonphenolic oxidations4-6 for the formation of biaryl linkages are not restricted to the classic cases ofintermolec-ular coupling reactions. There are also examples of intramolecular coupling reactions with the option of performing the reaction stereoselectively, provided that some electronic requirements are fulfilled ... 

Interestingly, seven-membered conjugated diyne complex 16 is produced by the acid-promoted Nicholas reaction of the dicobalt-coordinated bispropargylic complex (Equation (7)). The cyclization proceeds via an intramolecular coupling reaction between a propargyiic cation and an alkene produced after dehydration. The molecular structure of seven-membered diyne complex 16 is confirmed by X-ray analysis, although the decomplexation is not successfully carried out. 

A. Chenede, E. Perrin, E. D. Rekai, and P. Sinay, Synthesis of C-disaccharides by a samarium diiodide induced intramolecular coupling reaction of tethered sugars, Synlett p. 420 (1994). 

Intramolecular coupling reactions, in high-throughput catalyst discovery, 1, 362... 

Similar application to the construction of bisindole system was reported by Faul and co-workers. That is, the core structure (indole[2,3-a]carbazoles) (165) of rebeccamycin (61), which possesses potent antitumor and protein kinase C inhibitory properties, was synthesized by intramolecular coupling reaction of bisindolylmaleimides (164) with PIFA-BF3 Et20 [127] (Scheme 34). 

Hennings, D. D. Iwama, T. Rawal, V. H. Palladium-catalyzed (Ullmann-type) homocoupling of aryl halides a convenient and general synthesis of symmetrical biaryls via inter- and intramolecular coupling reactions. Org. Lett. 1999, 1, 1205-1208. 

The intramolecular coupling reactions of BrCH2CH CH(CH2) CH CHCH2Br, where w = 6, 8, and 12 (16), are shown in Table I. When n — 2, instead of the expected 1,5-cyclooctadiene, the main product is vinylcyclo-hexene, and when n = 4, instead of cyclodecadiene, the product is a mixture... 

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