Cyclonona-l,2-diene

Aryl- and alkylsulfonyl radicals have been generated from the corresponding iodides and added to, e.g., propadiene (la), enantiomerically enriched (P)-(+)-propa-2,3-diene [(P)-(lc)] and (P)-(-)-cyclonona-l,2-diene [(P)-(lk)] [47]. Diaddition of sulfo-nyl radicals may compete considerably with the monoaddition [48,49]. Also, products of diiodination have been purified from likewise obtained reaction mixtures, which points to a more complex reactivity pattern of these substrates towards cumulated Jt-bonds. An analysis of regioselectivities of arylsulfonyl radical addition to allenes is in agreement with the familiar trend that a-addition occurs in propadiene (la), whereas alkyl-substitution at the cumulated Jt-bond is associated with a marked increase in formation of /3-addition products (Scheme 11.7). 

The cationic allene complexes (32) (R, R , R , R = H or Me) undergo rotation about the n -bond with barriers that increase with increasing alkyl substitution of the allene - particularly at the syn-C-3 position. Intramolecular syn-anti isomerization of (32) is a higher-energy process but becomes easier with increasing substitution e.g. AC = 23.1 kcalmol-i (R = R = R = H, R =Me) and AG = 16.3 kcal mol" (R = R = R = R = Me). The mechanism for this isomerization involves a series of 1,2-shifts and a planar intermediate cannot be formed since chirality is retained in optically active j -cyclopentadienyl-( -cyclonona-l,2-diene)dicarbonyliron cation. 

The absolute configuration of (-)-cyclonona-l,2-diene has been established as iS) by an o.r.d.-c.d. correlation and by the extended chemical correlation shown (Scheme 14). The absolute configuration of the (+)-isomer of (232) was established by X-ray diffraction. 

Cyclic allenes undergo head-to-head cyclodimerization to give tricyclic 1,2-alkylidenccyclobu-tanes. Unsaturated cyclic allenes represent molecules with increased strain and often dimerize spontaneously. Whereas cyclonona-1,2-diene (28) requires heating of a neat sample to 138°C,38 the tetraene 31 has a half-life of 10 minutes at 0°C.39 The more strained cycloocta-l,2,4,6-te-traene (34) could not be isolated and only the dimeric cyclobutane 35 was formed on thermolysis of the tosylhydrazone precursor 33.40... 

Direct irradiation of an argon degassed 0.001 M pentane solution of cyclonona-1,2-diene (1) with wavelengths > 220 nm (Vycor filter) yielded bicyclo[6.1.0]non-l(9)-ene (6), cyclononyne 7 and tricyclo[4.3.0.0 ]nonane (3), ratio 94 3 3, as primary photoproducts. At low conversion of 1 (<20%) these isomers constituted more than 95% of the photoproducts higher conversions led to significant secondary reactions of bicyclo[6.1.0]non-l(9)-ene (6). 

Diimide reduction of the major photoproduct 6 gave bicyclo[6.1.0]nonane (8), while base-catalyzed isomerization of 6 provided two components in a 5 1 ratio, identified as bi-cyclo[6.1.0]non-l-ene (9) and cyclonona-1,2-diene... 

Vapor-phase direct irradiation of cyclonona-1,2-diene (1) gave a complex mixture of photoproducts, among which three-membered ring compounds 6 and 3, were present in 15 and 9% yield, respectively, the main product being the product nona-l,3,8-triene (40%) resulting from ring opening. 

A solution of cyclonona-1,2-diene (180 mg, 1.48 mol, prepared from cyclooctene ) and benzene (260 mg, 3.33 mmol) was placed into a 3.7-LVycor tube, the bottom portion of the tube was cooled to — 78 C, and the system was degassed by evacuating to ca. 0.15 Torr and backflushing with Nj several times. After evacuation to 0.15 Torr, the tube was allowed to warm to rt and was irradiated for 4.5 d in a Rayonet photoreactor fitted with 2537-A lamps. The reaction vessel was then cooled to — 78 °C and vented to N, and the product was collected with pentane. The pentane solution was filtered through neutral alumina and was concentrated under reduced pressure at 0"C to give 165 mg (92%) of a clear oil. Capillary GC analysis indicated 97% conversion to four major products. These were isolated on a preparative scale and identified as follows bicyclo[4.3.0]non-l(9)-ene (11 4%, / = 3.41 min) c -bicyclo(4.3.0]non-2-ene (9, 2%, / = 3.67 min) bicyclo[4.3.0]non-l-ene (10, 5%, = 3.90 min) and the product 3 yield 160 mg... 

The smallest isolable cyclic cummulene, cyclonona-l,2,3-triene (54), was made by a similar sequence. In this case the starting material, cycloocta-1,2-diene, which is unstable at room temperature, was made in solution at — 78 °C by cleavage of 8,8-dibromobicyclo[5.1.0]octane with methyllithium. In situ treatment of this diene from carbon tetrabromide and methyllithium at 0°C provided the dibromocarbene adduct 53 which was isolated and purified. This adduct rearranged to the rather unstable cyclonona-l,2,3-triene (54) on reaction with methyllithium at -78°C. ... 

Iodo-3-methoxy-fr r 5-cyclo-octene (150 R = I) and 2-iodo-3-methoxy-trans-cyclonona-1,6-diene (151 R = I) have been prepared by silver perchlorate-catalysed rearrangement of 8,8-di-iodobicyclo[5,l,0]octane and 9,9-di-iodobicyclo[6,l,0]non-4-ene, respectively. Treatment of (150 R = I) with methyl-lithium then water, deuterium oxide, or methyl iodide, gave (150 R = H, D, or Me), respectively. Treatment of (151 R = I) with methyl-lithium then water gave a product mixture which contained cyclonona-l,2,6-triene as the major component, whereas treatment with methyl-lithium then methyl iodide gave (151 R = Me) in good yield. (151 R = H or D) were obtained from (151 R = I) using lithium dimethylcuprate then water or deuterium oxide. 

Unlike non-strained acyclic allenes, cyclonona-1,2-dienes undergo cycloaddition reactions with halogenated ketenes, e.g. 1-methylcyclonona-l,2-diene reacts with chloromethylketen to give a mixture of adducts with (168) predominating. The cycloaddition of dimethylketen to optically active bicyclo[7,l,0]deca-4,5-diene gave U -(169).2° ... 

Cyclonona-l,2,5-triene, its 7-methoxy derivative, and cyclonona-l,2,5,7-tetraene, have been prepared by treatment of 9,9-dibromobicyclo[6,l,0]non-3-ene, its 5-methoxy derivative, and 9,9-dibromobicyclo[6,l,0]nona-3,5-diene, respectively, with methyl-lithium. In contrast, 9,9-dibromobicyclo[6,l,0]nona-2,6-diene undergoes transannular C—H carbene insertion however, cycIodeca-l,2,5,6-tetraene was prepared as a mixture of diastereoisomers from the bisdibromocarbene adduct of cyclo-octa-1,4-diene. Cyclonona-l,2,5,7-tetraene was found to dimerize rapidly. ... 

A reinvestigation of the addition of hydrogen bromide to cyclonona-1,2-diene has confirmed earlier results 3-bromo-cis-cyclononene was formed in neat acetic acid but 1-bromo-cis-cyclononene was obtained in the presence of an additional solvent such as diethyl ether or light petroleum. Similarly, addition of hydrogen bromide to cyclonona-1,2,6-triene in ether-acetic acid gave l-bromo-cis,cis-cyclonona-l,5-diene. ... 

Nine- and Ten-membered Rings.—Direct irradiation of cw-cyclononene in the vapour phase gives a mixture of nona-1,8-diene and vinylcycloheptane, whereas sensitized irradiation gives a mixture of nona-1,8-diene and five bicyclononanes. Metathesis of cis,cis-cyclonona-l,5-diene over a WCl -LiAlH catalyst gives a mixture of polymer (75%), starting material, cyclopentene, c/s-l,2-divinylcyclopentane, and an... 

A soln. of cyclonona-1,2-diene in tetrahydrofuran added to a sol. prepared from HgS04, dil. H2SO4, and tetrahydrofuran, refluxed 4 hrs. under Ng cyclonon-2-en-l-ol. Y 74%. G. Mehta, Org. Prep. Procedures 2, 245 (1970). 

Surprisingly, /ranj-tris-a-homobenzene (eni/o/exo-tetracyclo[6.1.0.0 . 0 ]nonane), and its hexamethyl derivative, at elevated temperatures (380-400°C in a flow system and 120°C, respectively) rearrange to frani-bicyclo[4.3.0]nona-3,7-diene and hexamethyl-rra 5-tricyclo[4.3.0.0 ]non-3-ene. It was shown by isotopic labeling, however, that this rearrangement also proceeds by way of a [ 2 + A -t- cycloreversion, which in these cases leads to highly reactive cis,trans,trans-cyclonona-l,4J-tnenes, which undergo a subsequent intramolecular [2-1-2] cycloaddition. ... 

Similarly, thermal isomerization of the [7,7- H2] isotopomer gave [3,7- H2]cyclonona-l,3,6-triene, and the [5,5,9,9- H4.] isotopomer gave [5,5,9,9- H4]cyclonona-l,3,6-triene. In contrast to these thermal ring expansions, chlorination of 1,5-bishomocycloheptadiene with tert-butyl hypochlorite yielded unrearranged, bridgehead chlorides, Silver(I) trifluoroacetate cleaved only one cyclopropane unit, without ring expansion, to afford 4-(methoxymethyl)bi-cyclo[5.1,0]octa-2,4-diene. ... 

These ring-expansion reactions were stereoselective in that only one diastereoisomer of the trans-cyclo-octenes and ds,trans-cyclonona-1,5-dienes was obtained. Rearrangement in methanol of 8,8-dibromobicyclo[5,l,0]octane gave the diastereoisomer of 2-bromo-3-methoxy-trans-cyclo-octene with the configuration shown in (118 X = H, Y = OMe). On warming to 190 °C this was equilibrated with (118 X = OMe,... 

Bicyclo[6,l,0]non-4-ene (535) may be isomerized with PdCl2(PhCN)2. At short reaction times, the trans-isomer (536) may be isolated, or the reaction conditions may be adjusted to allow the preparation of cis,cis-l,5-cyclonona-1,5-diene (537) in high yield. 

A number of studies of a-elimination have employed 9,9-dibromobicyclo[6,l,0]-nonyl derivatives and one has led to optically active cyclonona-2,3-dienone. Loozen and his group have found that whereas endo-a ky atior of the 9,9-dibromo-bicyclo[6,l,0]-nonanes and -nona-2,4,6-triene can be effected, compounds (398) and (399) afford allenes under the same reaction conditions. This has been ascribed to bishomoaromatic interaction favouring facile disrotatory cleavage of the carbenoid as depicted by (400). Under different conditions, Baird and Reese have found that the A -isomer of (398), the 3,5-diene, and (401) yield allenes and not carbene re-... 

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