Cyclooctane-diones

The central bond of bicyclo[4.2.0]octane-l,6-diol was cleaved by potassium periodate in water at room temperature to yield cyclooctane-1,4-dione.156... 

The reaction of 1,2-dicarbonyl compounds with amidrazones, semicarbazide, thiosemicarbazide and aminoguanidine has also been used for the synthesis of condensed 1,2,4-triazines. Cyclohexane-, cycloheptane- and cyclooctane-1,2-diones (489) with amidrazones (453) afford the cycloalkatriazines (490) (78HC(33)189, p.66l). 

A chloride-bridged structure has been proposed for the 1 1 adduct, [HgCl2(btaH)]2 (172). Mercury(II) benzotriazolate, Hg(bta)2, has been obtained from mercury(II) perchlorate, benzotriazole, and triethyl-amine in ethanol (172), and from mercuric oxide and benzotriazole (158). Mercuric acetate and chloride react with benzotriazole to form mixed mercury(II) salts, HgX(Ka) (X = MeC02 or Cl) (139). A dimeric structure (Fig. 13) with T-shaped coordination at mercury has been determined by X-ray diffraction methods (203) for the methyl derivative Hg(Me)(bta) (172). Cyclooctane-1,2-dione dihydrazide reacts with HgO... 

As recently reported, rhodium-dioxygen complexes such as RhCl(02)(PPh3)2 can transfer both dioxygen atoms to one mole of coordinated 1,5-cyclooctadiene to give cyclooctane-1,4-dione, without the intermediate formation of monoketone (equation 61). In the presence of excess PPh3, the reaction becomes slightly catalytic.212... 

Fullerene, Cgo, undergoes photochemical 2 + 2-cycloaddition with /V,A-diethyl-4-methylpent-3-en-l-yn-l-amine to produce the stable Cgo-fused cyclobutenamine that is photo-oxidized to the dihydrofullerenone amide in high yield.15 The photochemical 2 + 2-cycloaddition of arylalkenes with Cgo has been shown to occur by a two-step mechanism involving the formation of a dipolar or diradical intermediate in the rate-determining step.16 The 2 + 2-photo-cycloaddition of cis- and irons-1 -(/j-methoxyphen-yl)-l-propene to C6o produces only trans-2 + 2-adduct. This is consistent with a two-step mechanism.17 The 2 + 2-photo-cycloaddition of cyclic 1,3-diones to Cgo results in the formation of two furanylfullerenes, one chiral and the other achiral. None of the expected De Mayo cyclooctane-1,3-dione addition products were formed.18... 

Cyclohexan-l,3-dion addiert sich photochemisch an Acrylsauremethyl-ester zu den Cyclooctan-Derivaten 87a und 87 b (150). 

In a similar reaction, the reduction of 3,7-dimethyl-l,5-diazabicyclo[3.3.0]-octane-2,6-dione (VIII/127) to the cyclooctane derivative VIII/128 (Scheme VIII/23) was nearly quantitative. 

Cyclooctyne (75) can be prepared according to the usual rhethods of synthesis of acetylenic compounds. For instance, oxidation of the bishydrazone of cyclooctane-1,2-dione (74) " " or debromination of 1,2-dibromocyclooctene (76) with magnesium or the photolysis of the anion of I-tosyIamino-1,2,3-triazole derivative (77) gave cyclooctyne (75). 

Oxidation of cyclooctane-1,2-dione bishydrazone (1) with mercuric oxide yields mainly (2) along with a little cyclooctyne, triazoles, and their mercury derivatives.4... 

The generation of alkoxides in large-ring cycloalkanones results in the formation of relatively stable bicyclic hemiacetals. Thus, treatment of 70 with sodium borohydride results in the generation of 71 a, in equilibrium with its hydroxyoctanone tautomer, while treatment with phenyllithium gave the stable hemiacetal 71b (Scheme 3). Similar reactions were observed with cycloheptane- 1,4-dione and cyclooctane-1,5-dione however, no transannular hemiacetal formation was observed for hydroxycydohexanones [83]. 

In 2007, an interesting strategy for the generation of the enolate in a decarboxylative allylation was demonstrated by Schulz and Blechert. The enolate as well as the 7t-allylpalladium complex were formed in a decarboxylative de Mayo ring expansion reaction from 85 [107] and could be trapped in an asymmetric allylic alkylation (AAA) (Scheme 12.45). This allowed for the first time the preparation of enantioenriched substituted cycloheptane-1,4-dione and cyclooctane-l,5-dione derivatives 86 [108]. 

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