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Leptosperols A and B (1 and 2), two cinnamoylphloroglucinol–sesquiterpenoid hybrids featuring unprecedented 1-benzyl-2-(2-phenylethyl) cyclodecane and 2-benzyl-3-phenylethyl decahydronaphthalene ba...

Rate constants for the reactions of Cl atoms with cycloheptane, cyclooctane, cyclodecane, cyclohexanone, cycloheptanone, cyclooctanone, and cyclodecanone have been measured at 297 ± 2 K and atmospheric pressure of air using a relative rate method. n-Butane, with a rate constant of 2.05 × 10−10 cm3 molecule−1 s−1, was used as the reference compound, and the rate constants obtained (in units of 10−10 cm3 molecule−1 s−1) were cycloheptane, 4.22 ± 0.15; cyclooctane, 4.57 ± 0.15; cyclodecane, 5.13 ± 0.15; cyclohexanone, 1.79 ± 0.06; cycloheptanone, 2.46 ± 0.07; cyclooctanone, 2.97 ± 0.09; and cyclodecanone, 3.65 ± 0.15, where the indicated errors are two least-squares standard deviations and do not include uncertainties in the rate constant for the reference compound n-butane. Room temperature rate constants for the C5–C10 cycloketones indicate that the CH2 groups adjacent to the carbonyl group are almost totally deactivated toward H-atom abstraction by Cl atoms, and this also applies to acyclic ketones. A previous structure–reactivity relationship for Cl + alkanes has been extended to include acyclic and cyclic ketones. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 52–58, 2013

This paper uses DFT and G3(MP2) calculations to examine whether unbridged 10-membered rings can be made by (pi)6 + (pi)4 cycloadditions to (Z)- and (E)-hexatrienes, hexa-1,5-dien-3-ynes, (Z)-hexa-1,3-dien-5-ynes, hexa-1,2,3,5-tetraenes, and (Z)-hexa-3-ene-1,5-diynes. Cycloadditions to four 4pi reactants, buta-1,3-diene, butenyne, butatriene, and butadiyne, are explored. Thirty different basic cycloadditions are identified, and all are shown to be exothermic according to G3(MP2) calculations; strain energies in the products are comparable with that of cyclodecane itself, despite the presence of trans-alkene, alkyne, allene, cumulene, and s-trans diene moieties. The major obstacles to the isolation of 6 + 4 cycloaddition products are competing (pi)4 + (pi)2 cycloadditions and, especially, rapid Cope rearrangement of the products, but, in many cases, the judicious introduction of substituents can overcome these problems so that practical syntheses should be possible. Reactions between (E)-hexa-1,3,5-triene and s-trans-buta-1,3-diene are shown to have substantially lower activation energies than those involving (Z)-hexa-1,3,5-triene reacting with either s-cis- or s-trans-buta-1,3-diene. Conformationally locked derivatives of s-cis,s-cis (E)-hexa-1,3,5-trienes can lead to derivatives of (Z,Z,E)-cyclodeca-1,3,7-triene that are stable to Cope rearrangement, and reactions should proceed at close to ambient temperatures with suitable activating groups. We predict that it should be possible to prepare suitably substituted derivatives of at least 11 more highly unsaturated ring systems: (5Z,7Z)-cyclodeca-1,2,5,7-tetraene, (1Z,3Z)-cyclodeca-1,3-dien-7-yne, (2Z,7E)-cyclodeca-1,2,3,7-tetraene, (Z)-cyclodeca-1,2,3-trien-7-yne, (4Z,8E)-cyclodeca-1,2,4,8-tetraene, (Z)-cyclodeca-1,2,4,5,7-pentaene, (Z)-cyclodeca-1,2,4-trien-8-yne, (1Z,7E)-cyclodeca-1,7-dien-3-yne, (R,S,E)-cyclodeca-1,2,4,5,8-pentaene, cyclodeca-1,2,4,5,8,9-hexaene, and (R,S)-cyclodeca-1,2,4,5-tetraen-8-yne. In three other cases, we predict that cycloaddition will be followed by unusual and intriguing rearrangements. Cycloadditions can be accelerated by the presence of electron-withdrawing groups in either the 6pi or 4pi reactants. Transannular cyclizations of some products may lead to interesting stereocontrolled routes to 6,6- and/or 5,7-bicyclic structures.

Low-temperature 13C NMR spectra of cyclodecane (1) showed the presence of a minor conformation, assigned to the twist-boat-chair-chair (TBCC), in addition to the expected boat-chair-boat (BCB). If only the TBCC and BCB conformations were assumed to be appreciably populated, then a free-energy difference between the two conformations of 0.73 ± 0.3 kcal/mol could be obtained from the five area measurements over a temperature range of −148.6 to −131.0 °C, with populations of 5.2 and 94.8% for the TBCC and BCB conformations at −146.1 °C. However, an alternative description of the conformations of 1 was suggested by the ab initio calculations, which predicted that the twist-boat-chair (TBC) and TBCC conformations have comparable free energies and populations. Equal amounts of TBCC and TBC would give populations of 5.2, 5.2, and 89.6% and relative free energies of 0.72, 0.72, and 0.00 kcal/mol for the TBCC, TBC, and BCB conformations at −146.1 °C, based on the experimental areas at this temperature. The experim...

By means of a vibrating-tube densimeter, the densities at 25°C have been determined for binary mixtures of tetrachloromethane with a liquid (cyclodecane, cis-decahydronaphthalene, trans-decahydronaphthalene, bicyclohexyl, pentane) or a solid hydrocarbon (cyclododecane, cyclopentadecane, norbornane, adamantane, octahydro-4,7-methano-1H-indene). Excess molar volumes have been obtained in the whole mole fraction range for mixtures containing a liquid hydrocarbon. For solid cycloalkanes, apparent molar volumes have been evaluated in the whole range of miscibility. The partial molar volumes at infinite dilution\(\bar V^\circ \) have been calculated for all examined cycloalkanes and compared with those of n-alkanes. The dependence of\(\bar V^\circ \) upon the size and shape of the ring or cage structure of the solute is discussed. The capability of the Flory theory to reproduce VE for these mixtures is also tested.

The acyclis ω-tosyloxy-α-phenylsulfenyl ketone 1 a, derived from R-(−)-carvone, underwent intramolecular alkylation to give the cyclodecenone derivative 2a in good yield. Oxidation of the sulfide to the sulfoxide and thermal elimination of phenylsulfinic acid gave the ketone 8, presumably resulting from Diels-Alder dimerization of the exomethylene ketone 9, as the major product and the endocyclic α,β-unsaturated ketone 7 as the minor product. Reduction of 7 with LAH and treatment of the allylic alcohol product 10 with the sulfur trioxide-pyridine complex followed by LAH gave the (Z),(Z)-1,6-cyclodecadiene 11 and three other minor products, possibly including the sesquiterpene, helminthogermacrene (3). In contrast to the keto sulfoxide 2b, which mainly underwent exo elimination of phenylsulfinic acid, the hydroxy sulfoxide 12b, prepared from ketone 2a, underwent largely endo elimination to give the allylic alcohol 13 containing a (Z),(Z)-1,5-cyclodecadiene system.

The method of simulated annealing has been combined with an exact ring closure algorithm to locate the global minimum of hydrocarbon rings without energy minimization. A new program called ANNEAL-RING carries out simulated annealing by computation of the exact new positions of three or more atoms and then application of the Metropolis Monte Carlo accept-reject criterion [exp(-ΔE/RT)] with cooling. Cyclononane, cyclodecane, cycloundecane and cycloheptadecane were studied.

The p-methoxy-substituted pincer-ligated iridium complexes, (MeO-(tBu)PCP)IrH(4) ((R)PCP = kappa(3)-C(6)H(3)-2,6-(CH(2)PR(2))(2)) and (MeO-(iPr)PCP)IrH(4), are found to be highly effective catalysts for the dehydrogenation of alkanes (both with and without the use of sacrificial hydrogen acceptors). These complexes offer an interesting comparison with the recently reported bis-phosphinite "POCOP" ((R)POCOP = kappa(3)-C(6)H(3)-2,6-(OPR(2))(2)) pincer-ligated catalysts, which also show catalytic activity higher than unsubstituted PCP analogues (Gottker-Schnetmann, I.; White, P.; Brookhart, M. J. Am. Chem. Soc. 2004, 126, 1804). On the basis of nu(CO) values of the respective CO adducts, the MeO-PCP complexes appear to be more electron-rich than the parent PCP complexes, whereas the POCOP complexes appear to be more electron-poor. However, the MeO-PCP and POCOP ligands are calculated (DFT) to show effects in the same directions, relative to the parent PCP ligand, for the kinetics and thermodynamics of a broad range of reactions including the addition of C-H and H-H bonds and CO. In general, both ligands favor (relative to unsubstituted PCP) addition to the 14e (pincer)Ir fragments but disfavor addition to the 16e complexes (pincer)IrH(2) or (pincer)Ir(CO). These kinetic and thermodynamic effects are all largely attributable to the same electronic feature: O --C(aryl) pi-donation, from the methoxy or phosphinito groups of the respective ligands. DFT calculations also indicate that the kinetics (but not the thermodynamics) of C-H addition to (pincer)Ir are favored by sigma-withdrawal from the phosphorus atoms. The high nu(CO) value of (POCOP)Ir(CO) is attributable to electrostatic effects, rather than decreased Ir-CO pi-donation or increased OC-Ir sigma-donation.

We report the complexation of a series of n- and cycloalkanes by an anionic, metal−ligand cluster carrying a 12- charge. This host also encapsulates cyclodecane isomers such as adamantane, the dicy...

Cyclo-heptane, -octane, -decane, -dodecane and -octadecane have been fluorinated in the vapour phase with cobaltic fluoride. The perfluorocarbons obtained revealed varying degrees of skeletal rearrangements. Thus, cycloheptane gave perfluoro-cycloheptane and -methylcyclohexane; cyclooctane gave at least eight fluorocarbons including-bicyclo(3,3,0)octane and -cyclooctane; cyclodecane gave a complex mixture from which were isolated perfluoro cis- and trans-bicyclo(4,4,0)decanes but no perfluorocyclodecane; cyclododecane and cyclooctadecane gave complex fluorocarbon mixtures in which none of the fluorocarbons with the original cycloalkene skeleton could be detected. Tetradecafluorobicyclo(3,3,0)octane gave dodecafluorobicyclo (3,3,0)oct-1(5)-ene and decafluorobicyclo(3,3,0)octa-di-1(5), 2-ene when pyrolysed over iron gauze. The fluorination of cyclooctane also afforded 1 H -pentadecafluorocyclooctane which was dehydrofluorinated to tetradecafluorocyclooctene. This was converted to a range of derivatives including dodecafluorosuberic acid, 1,2-dichlorotetradecafluorocyclooctane, 1-methoxy tridecafluorocyclooctene and tetradecafluorocyclooctanone.

Irradiation of (eta/sup 5/-pentamethylcyclopenta-dienyl)(trimethyl phosphine) dehydroiridium (eta/sup 5/-C/sub 5/Me/sub 5/)(PMe/sub 3/)IrH/sub 2/ in saturated hydrocarbons using a 500 W Oriel focused-beam mercury lamp leads to extrusion of hydrogen and production of the hydrido alkyl iridium complexes (----HRIr). Competition experiments were used to measure relative rates at which the intermediate formed on hydrogen loss reacts with different types of C-H bonds. Relative to cyclohexane (1), these rates are: benzene (4), cyclopropane (2.65), cyclopentane (1.6), neopentane (1.14), cyclodecane (.23), and cyclooctane (.09). Reductive elimination of hydrocarbon occurs at elevated temperature, regenerating the intermediate, which may then react with another hydrocarbon acting as solvent. The factors which presumed to influence the rates of reaction of transition-metal complexes with saturated C-H bonds are discussed.

Crystals of the AgNO3-trans-cyclodecene adduct are orthorhombic, a = 5,47, b = 14,69, c = 26,73 A, space group Pbcn, with 4 formula units AgNO3·(C10H18)2 in the unit cell. The structure has been solved by the heavy-atom method and refined by full-matrix least-squares analysis of three-dimensional intensity data. The conformation of the trans-cyclodecene molecule has features in common with that of the cyclodecane ring, but the trans double bond is twisted about 40° from planarity. This deformation must contribute substantially to the strain-energy of trans-cyclodecene. The dependence of the twist-energy on the twist-angle is discussed.

The products isolated from the HOFMANN degradation of trans and cis 1,6-bis-trimethylammonio-cyclodecane (1a) depend on the reaction temperature. When carried out below 100° or when WITTIG'S low-temperature modification, i.e. with KNH2 in liquid ammonia, is employed, cyclodeca-l,5- and -1,6-dienes are formed almost exclusively, as shown by their hydrogenation to cyclodecane. When heated above 70° cyclodeca-l,5-diene (2) undergoes valency isomerisation to 1,2-divinylcyclohexane (4). This compound is obtained directly in ca. 45% yield besides 46% of non-isomerisable cyclodeca-l,5- and -1,6-dienes when the HOFMANN elimination is carried out at 120–150°. In addition, ca. 9% of octalines are formed by a transannular elimination reaction. The COPE elimination reaction of the bis-N-oxide of trans and cis 1,6-bis-dimethylarnino-cyclodecane (1c) at 120–150° affords a similar mixture of products containing ca. 43% of 1,2-divinylcyclohexane. The ease with which cyclodeca-l,5-diene undergoes valency isomerisation is attributed to the concomitant relief of strain and to the proximity of carbon atoms 1 and 6 in the trans/trans isomer.

The results of the X-ray analysis of 1,1,5,5-tetramethylcyclodecane-8-carboxylic acid do not correspond to a reasonable molecular structure. When used as a startingpoint for a strain-energy minimization calculation based on semi-empirical potential functions, they lead to two new conformations for the cyclodecane ring. It is shown that the X-ray results can be explained by assuming that the crystal consists of a random mixture of these two conformations.

1,6-trans-diaminocyclodecane dihydrochloride crystallizes in triclinic and monoclinic modifications. The structure of the triclinic form with a = 9,02; b = 6,19; c = 6,20 A; α = 96,7°; β = 99,3°; γ = 108,1°; space group P1; Z = 1, has been determined by analysis of the (001) and (010) projections and the conformation of the cyclodecane ring thereby established. Although the molecule, and its environment, is crystallographically only centrosymmetric, the carbon skeleton does not deviate significantly from the higher 2/m (C2h) symmetry. Of the torsion angles around the ring, 8 are close to 60° (syn-skew) the remaining 2 being 156° (nearly anti-planar). Some stereochemical implications of the cyclodecane conformation are briefly mentioned.

Degradation of the N-oxides and quaternary salts of the cis and trans forms of 1,6-bis-dimethylamino-cyclodeca-3,8-dienes (4 b) and (4 c), respectively, afforded mixtures of hydrocarbons C10H12 separable by gas chromatography after hydro-genation. In both cases a mixture of decalins, n-butykyclohexane,n-butylbenzene, cyclodecane and an unidentified tricyclic hydrocarbon C10H16 were obtained. However, COPE elimination yielded mainly trans-decalin (66%), HOFMANN elimination mainly the cis isomer (58-74%).

Crystals of 6-ketononanolide (oxacyclodeca-2,6-dione) are orthorhombic, a = 8.886, b = 16.407, c = 11.965 A, space group Pbca, with 8 molecules in the unit cell. The structure has been solved with the help of direct methods and refined by full-matrix least-squares analysis of three-dimensional intensity data. The conformation of the ring is similar to that previously observed in several cyclodecane derivatives, with the ring oxygen and carbonyl groups so situated as to minimize the number of transannular H … H contacts. Evidence for transannular O(ether) … C(carbonyl) donor-acceptor attraction is discussed.

The following vibrational spectra of cyclodecane have been investigated: (1) the IR.-spectrum of the liquid between 1500 and 450 cm−1 at room temperature; (2) the IR.-spectra of the solid in the surroundings of the melting point and at − 70 and − 170° C in the frequency range 1500…650 cm−1; (3) the Raman-spectrum of the liquid from 1500 to 300 cm−1 at room temperature.

Crystals of 1,1,5,5-tetramethylcyclodecane-8-carboxylic acid are monoclinic, a = 9.22 A, b = 14.81 A, c = 11.58 A, β = 111° 0′, space group P21/c with 4 molecules in the unit cell. The structure has been solved by direct methods and refined by full-matrix least-squares analysis of three-dimensional intensitiy data. The conformation of the ring differs from the previously observed cyclodecane conformation, but the detailed results are abnormal in a number of ways (extremely short CC bond lengths, wide CCC bond angles, large temperature factors). The possibility is discussed that the crystal structure is disordered.

Crystals of 1,6-trans-dibromcyclodecane are monoclinic, a = 7,94, b =5,65, c = 12,78 A, β = 106° 47′, space group P2, lc. The unit cell contains two centrosymmetric molecules. The crystal structure has been determined by analysis of the three prin- cipal projections. The ring skeleton has the same conformation as that found in all previously studied cyclodecane compounds, with the substituents in (IIe, IIe) positions.

The synthesis and some reactions of a series of linear 1,4-polyynes containing terminal acetylene groups (Ia–e) are described. Reaction of propargyl bromide (II) with ethynylmagnesium bromide (III) in the presence of CuCl gave 1,4-pentadiyne (Ia). Rearrangement of Ia with KOBut led to 1,3-pentadiyne (IV), while treatment with Br2 furnished 1,2,4,5-tetrabromo-1,4-pentadiene (V). Oxidation of Ia with O2, CuCl and NH4Cl yielded the linear dimer (VIa) [rearranged to 2,4,6,8-decatetrayne (VIII) with KOH] and linear trimer (VIb). Hydrogenation of the crude oxidation product gave saturated hydrocarbons derived from VIa, VIb, the linear tetramer (VIc) and the cyclic tetramer (VII), but none derived from the cyclic dimer or cyclic trimer of Ia. Similarly, oxidation of Ia with Cu(OAc)2 in pyridine and subsequent hydrogenation led to saturated hydrocarbons derived from VIa and VIb, but none derived from the cyclic dimer or cyclic trimer. In order to prepare cyclodecane as a comparison compound, the cycloethylenedithioketal (X) derived from cyclodecanone was treated with Raney Ni in boiling EtOH, but the reaction led mainly to cis-cyclodecene. Treatment of 1,4-dibromo-2-butyne (XIII) with an excess of III in the presence of CuCl yielded 1,4,7-octatriyne (Ib), 1,4,7,10,13-tetradecapentayne (Id) and 1,4,7,10,13,16,19-eicosaheptayne (Ie). Rearrangement of Ib with alkaline Al2O3, or KOBut at room temp gave 2,4,6-octatriyne (XVII), while treatment with boiling ethanolic KOH or KOBut in hot ButOH led to 2-ethoxy-2-octene-4,6-diyne (XVIIIa) or 2-t-butoxy-2-octene-4,6-diyne (XVIIIc), respectively. 1,4,7,10-Undecatetrayne (Ic) was prepared from crude Ia by conversion to the bis-Grignard derivative, followed by reaction with propargyl bromide (II) in the presence of CuCl.

1,1,6,6-Tetramethyl-cyclodecane and various of its derivatives have been synthesized. The influence of geminal methyl groups on the properties of cyclodecane derivatives, especially on their n.m.r. spectra, has been investigated.