Cycloheptatriene, reaction with

Cvcloheptane. strain energy of, 114 Cycloheptatriene. reaction with Br2. 527... 

Phosphorus pentachloride, for conversion of pentaacetylgluconic add to add chloride, 41, 80 for oxidation of cycloheptatriene to tropylium fluoborate, 43, 101 with cyanoacetic acid, 41, 5 Phosphorus tribromide, reaction with 1.5-hexadien-3-ol, 41, 50 Phthalic anhydride, reaction with L-phenylalanine to yield N-phthalyl-L-phenylalanine, 40, 82 Phthalic monoperacid, 42, 77 N-Phthalyl-i.-alanine, 40, 84 N-Phthalyl-/3-alanine, 40, 84 N-Phthalylglycine, 40, 84 N-Phthalyl-l-/5-phenylalanine, 40, 82... 

A transmetalation of the styrylcarbene chromium complex 62 in the presence of stoichiometric amounts of [Ni(cod)2] to give the nickel carbene intermediate 63 was applied to the synthesis of Cr(CO)3-coordinated cycloheptatriene 64 upon reaction with terminal alkynes [57] (Scheme 37). The formation of pen-tacarbonyl(acetonitrile)chromium is expected to facilitate the metal exchange. 

Electrocyclic reactions have been performed with three of the bridged [ 11 Jan-nulenones. Both 11 and 13, which both contain a cycloheptatriene unit, undergo Diels-Alder additions with dienophiles via their norcaradiene valence tautomers 41 and 43 and yield adducts of the type 42 and 44. Annulenone 13 was found to react only with 4-phenyl-l,2,4-triazoline-3,5-dione whilst 11 underwent reaction with a variety of dienophiles. 3,8-Methano[ 11 Jannulenone 12 contains a tetraene system and undergoes addition reactions, apparently of the (8 + 2)-type, at the termini of the tetraene system. Thus with maleic anhydride the adduct 46, the valence tautomer of the initial adduct 45, was isolated. 

The palladium-catalyzed trimethylenemethane reaction with tropanones was reported in 1987 by Trost and Seoane and is the first example of a [6 + 3]-cycloaddition.130 Chromium-mediated [6 + 3]-cycloadditions of two types have been described-one in which the chromium complex activates the six-carbon component and one in which the chromium complex activates the three-atom component. An example of the first type involves the reaction of a cycloheptatriene-Cr(CO)3 complex with azirines to give cyclic imines in moderate yields (Scheme 40).131... 

Starting from 2,4,6-octatriene and pivaldehyde, the conjugated homoallylic alcohol 8 is obtained as the sole product. Cycloheptatriene-derived complexes react with aldehydes and C02 to afford mixtures of the isomeric 1,3- and 1,4-cycloheptadienyl carbinols or acids, respectively. Interestingly, analogous reactions with methyl chloroformate or dimethyl carbamoyl chloride produce the conjugated dienyl ester 9 or amide 10 as unique products [19,20]. 

Later on, it was demonstrated that these heterocycles can undergo Diels-Alder reactions in the presence of an electrophile (Ss or Mel) and dienophiles <2002T1573, 2003HAC560>. These phosphoms-containing heterocycles were found to produce, upon reaction with tricarbonyl(cycloheptatriene)molybdenum(0) or tricarbonyl(mesitylene) tungsten(O), cr-complexes of the type L2M(CO)4 or I,(M(CO)( instead of 7t-complexes <1998EJI1079>. Some derivatives of this heterocycle were also found to display remarkable antibacterial activity <2005BML937>. 

Surprisingly, the partial reduction of quinone 137 is best achieved by refluxing in acetic or propionic acids (yield 67%). Thereby the acids suffer oxidative decarboxylation (82CL701 85BCJ515). Two further unexpected routes are based on the redox reaction with cycloheptatriene (85BCJ2072) and electrolysis under the conditions of the cyclic voltammetry measurements (87BCJ2497), respectively. 

Dehydration products have been observed from photosensitized oxygenation reactions with cycloheptatriene (304),220 AMialin (307) 222 3/1- and 3a-hydroxy-A4-cholestenes (312a and 312b, respectively),226,227 and 2-hydroxy-10-methyl-1,9-octalin (316).226... 

The products formed in these reactions are very sensitive to the functionality on the carbenoid. A study of Schechter and coworkers132 using 2-diazo-1,3-indandione (152) nicely illustrates this point. The resulting carbenoid would be expected to be more electrophilic than the one generated from alkyl diazoacetate and consequently ihodium(II) acetate could be used as catalyst. The alkylation products (153) were formed in high yields without any evidence of cycloheptatrienes (Scheme 33). As can be seen in the case for anisole, the reaction was much more selective than the rhodium(II)-catalyzed decomposition of ethyl diazoacetate (Scheme 31), resulting in the exclusive formation of the para product. Application of this alkylation process to the synthesis of a novel p-quinodimethane has been reported.133 Similar alkylation products were formed when dimethyl diazomalonate was decomposed in the presence of aromatic systems, but as these earlier studies134 were carried out either photochemically or by copper catalysis, side reactions also occurred, as can be seen in the reaction with toluene (equation 36). 

Decomposition of l-diazo-4-arylbutan-2-ones offers a direct entry to bicyclo[5.3.0]decatrienones and the approach has been extensively used by Scott and coworkers to synthesize substituted azulenes.137 Respectable yields were obtained with copper catalysis,137 but a more recent study24 showed that rho-dium(ll) acetate was much more effective, generating bicyclo[5.3.0]decatrienones (154) under mild conditions in excess of 90% yield (Scheme 34). The cycloheptatrienes (154) were acid labile and on treatment with TFA rearranged cleanly to 2-tetralones (155), presumably via norcaradiene intermediates (156). Substituents on the aromatic ring exerted considerable effect on the course of the reaction. With m-methoxy-substituted systems the 2-tetralone was directly formed. Thus, it appeared that rearrangement of (156) to (154) was kinetically favored, but under acidic conditions or with appropriate functionality, equilibration to the 2-tetralone (155) occurred. 

In addition to their reactions with alkenes and carbanions as nucleophiles benzhydryl cations react with hydride donors.282 284 These hydride transfer reactions show the same linear dependence of log k upon E as the reactions with alkenes and the same constant relative selectivity, that is with slopes of plots close to 1.0, for structures ranging from cycloheptatriene to the... 

Satake et al. have described the mechanistic aspects of the formation of 2-methoxy-277-azepine derivatives lla-d from 377-azepines lOa-d upon reaction with bromine <2003H(60)2211> (Scheme 1). Unlike the situation observed with cycloheptatrienes, delocalized azatropylium salts were not formed from the reaction of 377-azepines with bromine in the absence of an alcoholic solvent. Reaction of 12 with bromine gave 13 plus the bis-ether 14 and bromomethane. The product 14 was also observed in the reaction of 12 with NBS (0.5 equiv) with 1 equiv of 7V-bromosuccinimide (NBS) 12 afforded the succinimido-substituted derivative 15, which upon elimination of HBr in the presence of base gave the 277-azepine 16 (Scheme 2) <2003H(60)2211>. 

Phenyl-l,2,4-triazoline-3,5-dione acts as a dienophile by in situ reaction with butadiene, cyclopentadiene, cycloheptatriene, and bicyclohepta-diene (62TL615). Thus, it is possible to compare the reactivity of the cis-azo dienophile (110) with trans-azo dienophiles, such as ethyl azodicar-boxylate, which has been observed to undergo alternate modes of reaction when used with less reactive or hindered dienes. Treatment of (110) with several dienes resulted in exclusively Diels-Alder addition. The results are summarized in Table III. 

While 154-157 are specific products for la, complexes of the type of 153a are the predominate products when 152 is reacted photochemically with acetylene (221), olefins (750,222,225), dienes, trienes, and tetraenes (224-226). In contrast to a previous report (227), 1,3,5-cycloheptatriene reacts with 152 like the other unsaturated hydrocarbons. Similar reaction products are obtained with lc as the diene component [Eq. (76)]. Although complexes comparable with 154,156, and 157 are missing, a trinulear species is formed... 

Cyclopropene also adds to less reactive, acyclic, dienes218), though it is worth noting that the reaction with cyclohexadiene only proceeds in 10% yield 219). Addition of a range of alkylcyclopropenes to thiophene dioxides leads to cycloheptatrienes, presumably by cheletropic elimination of sulphur dioxide from the intermediate adduct 220) ... 

Reaction with cyclopentadienones or their acetals also occurs readily hydrolysis of the acetals and decarbonylation also leads to cycloheptatrienes, while hydrogenation prior to the elimination produces cyclohepta-1,4-dienes 221 222) ... 

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