Cyclohepta-2,4 -dien-1 -ones

In the case of chiral base catalysis of the E2 elimination, enantioenriched 7-hydroxyenones from the corresponding endoperoxides were obtained <2006JA12658> in fact, a one-pot asymmetric 1,4-dioxygenation of 1,3-cyclohepta-diene by sequential reaction with singlet oxygen and 5 mol% chiral catalyst provided the 7-hydroxyenones 80 in 90% yield and 92% ee (Scheme 18). 

In elegant configurational studies of biphenyls, Mislow and his associates (Newman et ah, 1958 Mislow et al., 1962) have used the Meerwein-Ponndorf-Verley reduction to determine absolute configuration. Kacemic 4, l"-dinitro-l,2,3,4-dibenz-l,3-cyclohepta-diene-6-one (DNDBCH-6-one) was partially reduced (7 hours reaction time) with S-(- -)-methyl-terf-butylcarbinol and aluminum tert-butoxide to (—)DNDBCH-6-ol. The unreacted ketone was dextrorotatory. The (+)-DNDBCH-6-one was reduced to (-1-)-... 

When treated with fuming sulfuric acid and then with water, decafluoro-cyclohepta-1,4-diene gives hexafluoro-l,5-dihydroxy-8-oxabicyclo(3 2 l)octan-3-one rather than octafluorocyclohepta-2,6-dienone, which is a probable intermediate [28] (equation 31)... 

Dibenzo[a d] cyclohepta-1,4-diene-5-one 3-Dimethylaminopropanol Magnesium Chloride Hydrogen Peroxide... 

The starting material can be prepared in known manner from dibenzo[a,d] cyclohepta-1,4-diene-5-one by a Grignard reaction with 3-dimethylaminopropyl magnesium chloride, hydrolysis and dehydration of the resulting carbinol. 

Even with the highly reactive dienophile cyclohepta-2,6-dien-4-ynone, generated from 1-aminocycloheptatriazol-6-(1 H)-one by lead(IV) acetate oxidation, only the adduct of benzene oxide 3 can be isolated.231... 

It has been reported that irradiation of bicyclo[5.1.0]octa-3,5-dien-2-one (63) in methanol leads to a mixture of racemic tricyclo[4,2.0.03,5]oct-7-en-2-one (65), 37, and cyclohepta-l,3,5-triene35). Control of the reaction was also tried in expectation... 

Attempts were reported119,129 to synthesize the ortho-linked diphenyl cyclo-propenone phenanthreno cyclopropenone 173 by dehydrohalogenation of the dibromo derivative 174 of dibenzo cyclohepta-l,3-diene-6-one. The only product isolated was the anhydride 175 of phenanthrene-9-carboxilic acid, which was shown not to arise from 173l29 ... 

Scheme 6.108 Products ofthe interception of 1,2,4,6-cyclohepta-tetraene (5) with 1,3-diphenylisobenzofuran, anthracenes, 2,5-dimethyl-3,4-diphenylcyclopenta-2,4-dien-l-one, methyl 2-pyrone-5-carboxylate, tropones, 8,8-dicyanoheptafulvene and 1,3,5-cycloheptatrienes.

The intermediacy of the radical cations of isotoluenes (methylenecyclohexadienes) and their derivatives is a common feature in organic mass spectrometry however, it is widely ignored because of the rather difficult experimental access to neutral isotoluenes. Again, the reader is referred to the discussion on methylenecyclohexadienes in the 1990 review on ionized alkylbenzenes7. An early paper by Lifshitz and Bauer150 on mass spectrometry of bicyclo[3.2.0]hepta-2,6-diene, another C7H8 isomer, as well as of bicyclo[3.2.0]hept-6-ene and one of its isomers, cyclohepta-1,3-diene, may also be mentioned in this context. 

Ring closure to cyclobutanes via valence isomerization of cycloocta-l,3,5-trienes is also possible when carbonyl functions are present in the ethane fragment. Thus, reaction of cyclohepta-2,4,6-trienone (tropone) with diazopropane gives 8,8-dimethylcycloocta-2,4,6-trienone (16, R = H), which rearranges quantitatively to 8,8-dimethylbicyclo[4.2.0]octa-2,4-dien-7-one (17, R = H).67... 

Dibenzo[a,d]cyclohepta-l,4-diene-5-one 3-Dimethylaminopropanol magnesium chloride Hydrogen peroxide... 

The 8 + 2-cycloaddition of 2//-cyclohepta[Z>]furan-2-one (155) with acyclic 1,3-dienes provides a facile route to hicyclo[5.3.0] ring systems (156) (Scheme 61). 2H-Benzo[h]thiete in the o-quinoid form undergoes 8- -2-cycloaddition with 1,3-dithiolane-2-thione, l,3-dithiole-2-thiones, and adamantanethione to produce 4/7-1,3-henzodithianes. ... 

The ethylene ketal of cyclohepta-2,6-dien-l-one afforded the carbene addition product 5 to one isomerized double bond. ... 

CCRIS 2780 Dibenzo(a,d)cycloheptadien-5-one Di-benzo(a,d)cyclohepta(1,4)dien-5-one 5H-Dibenzo-(a,d)cyolohepten-5-one, 10,11-dihydro- Dibenzo-(b,f)cycloheptan-1-one Dibenzocycloheptenone Di-benzosuberan-5-one Dibenzosuberone 2,3 6,7-Di-benzosuberone Dibenzsuberone 10,11-Dihydro-5H-dibenzo(a,d)cyclohepten-5-one 10,11 -Dihydrodibenzo-... 

Rhodium catalysis is also of crucial importance in the conceptually new type of synthesis of cyclohepta-2,4-dien-l-ones (e. g. 12) by Huffman and Liebeskind. [8] The rearrangement of 4-cyclopropyl-2-cyclobuteno-nes such as 11, which are accessible in a few steps from squaric acid, [9] is similarly achieved with Wilkinson s catalyst (Scheme... 

The catalytic reaction of complex 49 with dtbcH2 and dioxygen is less selective than that of 50. In addition to the formation of dtbq and 3,5-di-ter -butyl-l-oxa-cyclohepta-3,5-diene-2,7-dione, some muconic acid anhydride and 2-pyrone derivatives are also produced as a result of both intra- and extradiol insertion of one of the oxygen atoms from dioxygen. Such products are consistent with the mechanism in Scheme 10, with the proviso that both the rhodium and iridium systems share the same mechanism, at least in the initial stages of the reaction. 

Dibenzo [a, d) cyclohepta-1,4-diene-5-one Amitriptylin oxide Dibenzo [a,e)cycloheptatrien-5-one Cyproheptadine 5 H -D ibenzo [a, d) cy do heptane Protriptyline... 

A soln. of er butyl acetate in THF added to i-Pr2NLi in the same solvent at —78°, after stirring for 1 h a soln. of tropone in THF added, the mixture stirred for 15-25 min, and poured into cold (0-10°) 5% aq. HCl 2-(2- er butoxy-2-oxoethyl)cyclohepta-3,5-dien-l-one. Y 93%. cf. Synth. Meth. 17, 764. The method was also applicable to the preparation of 2-subst. tropones by 1,8-addition-elimination with 2-chlorotropone. F.e.s. J.H. Rigby et al., J. Org. Chem. 53, 4596-8 (1988). 

The intramolecular Diels-Alder reaction of 7- cyclopent-3 -en-r-yl)cyclohepta-2,4-dien-l-one to give (192) was a key step in a synthesis of iceane. Nickelocene reacts with octachlorocycloheptatriene to give (193) which undergoes a spontaneous intramolecular Diels-Alder reaction to give (194). ... 

Irradiation of cycloheptene in the presence of mercury gave a mixture of norcarane, vinylcyclopentane, hepta-1,6-diene, and other minor products. Deuterium labelling showed that the norcarane arose via a 1,2-hydrogen shift followed by ring-closure. The photochemical conrotatory ring-closure of all possible 1,3-dimethyl- and 1,4-dimethyl-cyclohepta-1,3-dienes has been carried out. " ( )-Grandisol has been synthesized from eucarvone, the first step in the synthesis being the photoisomerization of eucarvone to l,4,4-trimethylbicyclo[3,2,0]hept-6-en-2-one. °... 

Ring-expansion Reactions. More work has been reported on the formation of seven-membered rings by rearrangement of divinylcyclopropanes. For example good yields of cyclohepta-1,4-dienes were obtained by treatment of P-iodo-aP-unsaturated ketones with the mixed cuprate LiCu(PhS)(2-vinylcyclopropyl), and thermolysis of the adduct mixture so obtained 3-iodocyclohex-2-enone was converted into bicyclo-[5,4,0]undeca-l(7),4-dien-8-one (75%) in this way. Vinylcyclopropyl-lithium... 

Interratingly, irradiation for 6 h of the 1 1 complex 61 compc d of 8 a and 58 which had been prepared by keeping a solution of 8a and an equimolar amount of 58 in benzene-hexane at room temperature for 12 h (colorless needles of mp 133 to 136 °C) gave the optically active photocyclization product (—)-bk yclo[4.2.0]oct-7-en-2-one (62) Qa]p —60.6 (c 0.18, CHCI3)] in quantitative yield The photocyclization reaction is in contrast to the photodimerization of 58 in 59. In the case of 61, the photodimerization of 58 is probably prevented by steric hindrance. It is almost certain that one optical conformer of 58 is included in 61, but a real proof of this fact requires an X-ray structural study in the future. However, the formation of the optically active 62 is valuable, because photoreaction of 58 in solution does not give any intramolecular photocyclization product It has been reported that irradiation of bicyclo[5.1.0]octa-3,5-dien-2-one (63) in methanol leads to a mixture of racemic tricyclo[4.2.0.0 ]oct-7-en-2-one (65), 37, and cyclohepta-l,3,5-triene Control of the reaction was also tried in expectation... 

In cyclohepta-l,3-diene, which has C, symmetry, all the carbon atoms except the one remotest from the double bonds are coplanar, giving the molecule a partly open envelope configuration (20), with flap angle a = 73 out-of-plane. Butadiene-like coi jugation is observed. Like cyclohexa-1,3-diene, cyclo-octa-l,3-diene has its strain relieved by a twist (here 38°) about the =C-C= bond, but the molecule appears to possess no elements of symmetry. Formula (21) shows a projection down the =C-C= bond. 

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