Tricyclo deca-3,5-diene

The reaction of oxepin with dimethyl 5-oxo-2,3-diphenylcyclopenta-l,3-diene-l,4-dicarboxy-late takes a different course. Two products 7 and 8 can be isolated, 7 is the [4 + 2] adduct of the cyclopentadienone across the central C-C double bond of the oxepin, the other, 8, is thought to be a [4+6] cycloadduct across the triene system of the oxepin.237 In boiling benzene, the [4 + 2] adduct 7 undergoes no cycloreversion, but rearranges to the tricyclo[5.3.02,4]deca-5,8-dien-10-one system.237 The [4+6] adduct, however, is stable under thermal conditions. 

CYCLOBUTADIENE IN SYNTHESIS endo-TRICYCLO[4.4.0.02 5]DECA-3,8-DIEN-7,IO-DIONE... 

The synthesis of fUido-tricyclo[4.4.0.02 5]deca-3,8-dien-7,10-dione and verification of its endo-configuration has been reported earlier.3 This adduet is a useful starting material for the syntheses of tetracyclo-[5.3.0.02 6.03 10]deca-4,8-diene,s tricyclo[4.4.0.02 5]deca-3,7,9-triene,6 cis, syn, cjs-tricyclo[5.3.0.02,6]deca-4,8-dien-3,10-dione,7 and 4-oxahexa-cyclo[5.4.0.02 6.03 10.05 9.08,11]undecane.a... 

The recent upsurge of interest in systems of theoretical interest demands practical syntheses of several important compounds. These are BICYCLO[2.l.0]PENT-2-ENE, BENZOCYCLOPROPENE, 1,6-OXIDO[10]ANNULENE, and others. ewdo-TRICYCLO[4.4.0.02 5]-DECA-3,8-DIENE-7,10-DIONE is utilized as a model for the use of CYCLOBUTADIENE IN SYNTHESIS, and a stable monomeric ketene, icri-BUTYLCYANOKETENE offers opportunities for further studies of this interesting species. 

Dimethyl tricyclo[4.2.2.02 -5]deca-3,7-diene-9,10-dicarboxylate adds bromine and iodine only to the less hindered double bond to give the syn 1,2-addition product of the cyclobutene moiety79. The product composition from this compound depends on the temperature and the solvent. At high temperatures, the 1,2-addition predominates over the transannular reaction, but this predominance is small in a solvent like chloroform and is lost in a protic solvent such as acetic acid (equation 47). 

Electrophilic addition of IN3 to the tricyclo[4.2.2.02,5]deca-3,7-diene derivative 60 has been reported92,93 to give exclusively or predominantly the syn azido iodide 61... 

The stereochemistry and the mechanism of the electrophilic additions to tricyclo[4.2. 2.02,5]deca-3,7-diene derivatives have been studied frequently, although some unambiguous... 

Flash vacuum pyrolysis of tricyclo[7.1.0.04,6]deca-2,7-diene 544 is accompanied by a long cascade of rearrangements leading to various azulenes (equation 214)266. The structures of these products were determined by using the chlorine atoms as labels for the 13C NMR measurements. 

Trimethyl-4-oxa-3,5-diaza- tricyclo[6.1.1.01 e]deca-2,5-dien--5-oxid -3-oxid... 

Chelate complexes of the type [PdX2(diene)] (X = Cl, Br) are readily formed by the dienes hexa-1,5-diene (124), bicyclo 2,2,lJhepta-2,5-diene (1, 7) tricyclo[4,2,2,0]-deca-triene and -diene derivatives (10), cyclo-octa-1,5-diene and dicyclopentadiene, but not dipentene (43). These may be converted to complexes of the types [Pd2X2(dieneOR)2] and [PdCl(dieneOR)-(amine)] (R = alkyl) (43), and their properties indicate that they have similar structures to the platinum complexes (XXXI) and (XXXIII). 

A clean eiectrocyclic ring opening occurred at mild temperatures with the strained tricy-clo[4.3.0.07-9]nona-2,4-diene (3a) and tricyclo[4.4.0.02 5]deca-7,9-diene (3b) to give cycloocta-1,3,5-triene derivatives 4.182... 

Bei der photosensibilisierten Dimerisation des Cydopentadiens bei —10 °C entstehen endo-Dicydopentadien (Formel 30), exo-Dicydopentadien (Formel 31) und als C4-Cydomerisat das trans-Tricyclo[5,3,0,02.a]deca-3,9-dien (Formel 32) im ungefahren Verhaltnis 1 1 1 (nach Korrektur fiir die thermische Dimerisation) (139, 306). 

Similar polymerisation behaviour was exhibited by exo- and endo-dicyclopen-tadiene (tricyclo[5.2.1.026]deca-3,8-diene) [10] ... 

Hexamethyl-3,8-dioxa-1,5,6,10-ietraaza-2/. 7ks-diphosph tricyclo[5.3.0.01 t]deca-4,9-dien 65... 

Retrocycloaddition Many cycloaddition reactions require moderate heating to overcome the activation energy, but if it is heated too much the equilibrium will favour cycloreversion or retrocycloaddition. For example, cyclopentadiene slowly undergoes cycloaddition with itself one molecule of cyclopentadiene acts as a [4ir]-electrons diene and the other as a [2tt]-electrons dienophile. The product is an endo-tricyclo[5.2.1.0]deca-3,8-diene (8.4), often called dicyclopentadiene. The product 8.4 gives back cyclopentadiene on heating at 150° C for an hour. 

Thia-tricyclo 5.2,1.02- deca-4,8-dien 5,6-Dichlor- -3,3,-dioxid V/lc, 1047... 

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