Showing papers on "Cyclopropane published in 1975"

Synthesis of (±)-presqualene alcohol, (±)-prephytoene alcohol, and structurally related compounds

Abstract: The stereochemistry of the base-catalysed addition–elimination method for cyclopropane ring synthesis, employing a βγ-unsaturated phenyl sulphone and an αβ-unsaturated ester, has been examined. The olefinic geometry of the βγ-unsaturated sulphone is retained in the product, and the unsaturated side chain and the ester function emerge trans about the ring, with substantial stereoselectivity. On the other hand, the geometry of the double bond of the αβ-unsaturated ester becomes equilibrated in the anion addition product. Thus the resulting cyclopropanes are produced without a stereoselective preference based on the geometry of the original αβ-unsaturated ester. This work has led to the synthesis of ethyl 2,2-dimethyl-trans-3-[(1E,5E)-2,6,10-trimethylundeca-1,5,9-trienyl]cyclopropanecarboxylate (40) and the corresponding cyclopropylmethanol (42), representing one side of the presqualene molecule, and to the pair of C-2 epimeric diterpenoid ethyl 2-[(E)-4,8-dimethylnona-3,7-dienyl]-2-methyl-trans-3-(2-methylprop-1-enyl)cyclopropanecarboxylates (44) and (45) and the corresponding alcohols (47) and (48), representing the other side of the presqualene molecule. Lower prenylogues were also studied.By using phenyl 3,7,11-trimethyldodeca-2,6,10-trienyl sulphone (37) and ethyl (2E,6E)-3,7,11-trimethyl-dodeca-2,6,10-trienoate (39; R = Et), the stereochemically controlled synthesis was developed to give two stereoisomers of presqualene esters (49) and (50), which were separated and reduced to give (±)-natural presqualene alcohol (53) and the C-2 epimer (54); tritiated samples were also prepared. Chemical and biological comparison with natural presqualene alcohol, the C30 compound involved in squalene biosynthesis, confirmed the identification. An n.m.r. study with shift reagents was used to investigate the stereochemistry of these and related subsituted cyclopropanes.Condensation of the C20 sulphone (64) with the C20 ester (62) led, in a similar synthesis, to the C40 cyclopropane carotenoid precursor (±)-prephytoene alcohol (68) and its C-2 epimer (69).

Microwave spectrum of cyclopropane(1,1)dicarbonitrile

Abstract: The microwave spectrum of cyclopropane(1,1)dicarbonitrile has been studied between 18 and 40 GHz by modulated microwave double resonance spectroscopy. The molecule is a b‐type asymmetric rotor with κ ? −0.20. Lines with J values up to 27 have been fit to a quartic Hamiltonian. Rotational constants obtained from this fit include A = 3779.65 MHz, B = 2549.21 MHz, C = 1726.75 MHz. The CC bond opposite the substituents has been estimated from the planar moment to be 1.485±0.01 A.

The Far Infrared Spectra and X-Ray Powder Diffraction Patterns of the Structure I Hydrates of Cyclopropane and Ethylene Oxide at 100 °K

Abstract: This paper presents the far-infrared spectrum and X-ray powder diffraction pattern of the structure I hydrate of cyclopropane at 100 °K, and the powder diffraction pattern of the isostructural ethylene oxide hydrate at 100 °K. Between 360 and 100 cm−1 the absorption by cyclopropane hydrate is essentially identical to that by ethylene oxide hydrate, but is shifted to low frequency by about 2%. This shift is undoubtedly related to the hydrogen bonds being slightly longer in cyclopropane hydrate, whose cubic lattice parameter is 11.98 ± 0.02 A compared to 11.89 ± 0.02 A for ethylene oxide hydrate, both at 110 ± 20 °K. The absorption by cyclopropane hydrate below 100 cm−1 decreases rapidly with decreasing frequency; this confirms that the absorption plateau observed for ethylene oxide hydrate between 100 and about 50 cm−1 is due to primarily rotational vibrations of ethylene oxide. A recent statement, that the orientational disorder of the water molecules need not be invoked to explain the far infrared spectr...

Pesticidal cyclopropane derivatives

Abstract: Cyclopropane derivatives of the formula ##EQU1## wherein each R is alkyl, R.sub. 3 is optionally substituted hydrocarbyl, each Hal represents halogen, and Z represents an optionally substituted phenyl group are useful as pesticides.

Electroorganic Chemistry XVIII Anodic Oxidation of Substituted Cyclopropanes

Abstract: The anodic oxidations of polyalkyl-substituted cyclopropanes (1–3) and spiro[2.n]alkanes (4–6) were carried out in methanol. Monomethoxyolefin and dimethoxy compound resulted from the selective cleavage at the most substituted carbon–carbon bond. The decrease in the oxidation potential brought about by the substitution of the one methyl group was observed to be about 0.3 V vs. SCE. The analysis of the products and oxidation potentials of the cyclopropanes suggested that the σ-electron transfer from cyclopropane to the anode may be the initiation process and that the stereochemistry at the surface of the solid electrode plays an important role in this anodic oxidation.

Fluororganische Synthesen IV, 1‐Fluor‐1‐organyl‐cyclopropane und andere Cyclopropan‐Derivate durch Anlagerungsreaktion von «Nachfolge‐Carbenen»

Abstract: Fluoroorganic Syntheses IV: 1-Fluoro-1-organyl-cyclopropanes and other Cyclopropane Derivatives by Addition of „Successor-Carbenes” Treatment of chlorodifluormethane or dichlorodifluoromethane with methyllithium in the presence of an olefin affords 1-fluoro-1-methylcyclopropanes in fair yields. Depending on the particular reaction conditions, 1,1-difluorocyclopropanes, 1,1-dimethylcyclopropanes and 1-chloro-1-methylcyclopropanes may be obtained as well. Butyllithium and phenyllithium give rise to analogous products.

Carbon-13-magnetic resonance spectra. Synthetic presqualene esters, related cyclopropanes, and isoprenoids

Abstract: 13 C N.m.r. spectra of isoprenoids, both acyclic and containing a cyclopropane ring, have been measured. These include cis- and trans-chrysanthemic acid and its relatives, presqualene esters, and compounds containing part-structures of the latter. The data are employed to derive stereochemical assignments in the presqualene series.

Functionally Substituted Cyclopropanes

Abstract: Progress in the synthesis of functionally substituted cyclopropanes is surveyed together with certain of their properties as well as aspects of their structure and the transmission of electronic effects through the cyclopropane ring. A list of 225 references is included.

Kinetics of the decomposition of some Δ1-pyrazolines

Abstract: Thermal decomposition of a series of 4- and 5-alkyl-substituted 3-methyl-3-methoxycarbonyl (or 3-acetyl)-Δ1-pyrazolines has been investigated. The relative rates for the decomposition of these compounds were given. Two mechanisms are proposed, one for the formation of olefin and the other for the formation of cyclopropane, to account for the observed kinetic results and product distribution.

Process for the preparation of cyclobutanones

Abstract: A B S T R A C T A process for the preparation of 2-halocyclobutanones or 2-halocyclobutenones by reacting a 2-haloacylhalide in an inert aprotic polar solvent with an ethylenically unsaturated compound or an alkyne at a temperature above 5°C in the presence of zinc and/or tin. The compounds which are prererably prepared in diisobutylketone are precursors or cyclopropane carboxylic acids.

Hydrogen fluoride vibrational energy distributions for the reactions of fluorine atoms with cyclanes

Abstract: The hydrogen fluoride infrared chemiluminescence produced by the reactions of fluorine atoms with cyclopropane, cyclopentane, and cyclohexane have been studied. The emission data were used to determine the vibrational energy distributions for the abstraction of hydrogen from the secondary carbon–hydrogen bonds of these small cyclic hydrocarbons. The fraction of reaction exothermicity going into vibrational excitation of hydrogen fluoride was as follows: c-C3H6, 45%; c-C5H10, 53%; c-C6H12, 49%. The slightly lower fraction for the cyclopropane system may indicate that its radical reorganization energy is not completely available for excitation of product HF.

Process for the preparation of cyclopropane derivatives

Abstract: GEM-DIHALOCYCLOPROPANE DERIVATIVES ARE PREPARED BY REACTING OLEFINIC COMPOUNDS WITH A DIHALOCARBENE IN THE PRESENCE OF AN IMPROVED CATALYST.

Insecticidal composition containing cyclopropane-carboxylate

Abstract: An insecticidal composition and method containing a compound of the formula, ##EQU1## wherein R is hydrogen or methyl group, which is harmless to warm-blooded animals.

Further rearrangements of cyclopropyl epoxides. Formation of cyclobutanes and cyclobutenes

Abstract: Cyclopropyl epoxides having aryl substituents in the 1-position of the cyclopropane ring underwent acid-catalysed rearrangement to 1- and 2- arylcyclobutenes; in methanol they formed stereoisomeric 1-aryl-1-methoxycyclobutanes. A cyclopropyl epoxide substituted in the 2-position of the cyclopropane ring by geminal methyl groups rearranged to a hexa-2,5-dien-1-ol rather than a 3,6-dihydro-2H-pyran. Except in the formation of stereoisomeric pent-2-en-1-ols, cyclopropyl epoxides unsubstituted in the alicyclic ring underwent typical epoxide reactions.

Ring C Functionalized Diterpenoids. Part IV. Minor Products from the Cleavage of the Cyclopropane Ring in Methyl ent-Trachyloban-19-oate with Thallic Acetate

Abstract: Structures are assigned to seven minor products (6b, 9, 11b, 12b, 13b, 16, and 25b) obtained from treatment of methyl ent-trachyloban-19-oate (1) with thallic oxide in acetic acid. The mechanism of the oxidative cleavage is discussed. Formation of the major products, described earlier, and all but one (25b) of the minor products may be rationalized in terms of initial scission of the C13—C16 bond.

7,14-Cyclo-dihydro-codeinon

Abstract: (5α,9α,13β,14β)-4,5-Epoxy-9-hydroxy-3-methoxy-17-methyl-hasubanan-6-one-hydrochloride (6 a·HCl) reacts with dimethyl sulfate to give the sulfate7 which yields the cyclopropane derivate10 on treatment with aqueous NaOH. The structure of 7,14-cyclo-dihydrocodeinone (10) was established on the basis of1H- and13C-NMR-spectroscopy.

Photolysis of Cyclopropane at 1470 and 1634 Å

Abstract: The vacuum-ultraviolet photolysis of cyclopropane in the gas phase has been investigated at room temperature at excitation wavelengths 1470 and 1634 A. Primary processes are discussed in terms of variations of product yield as a function of conversion and in the presence of additives such as NO, C2D4, and H2. The relative yields of decomposition are determined at both wavelengths. The main primary process is cyclo-C3H6+hv→C2H4+CH2, the yield being 67% at 1470 A (69% at 1634 A). The observed product yield responsible for methylene is much less than that for ethylene. However, the yields become equal in the photolysis of cyclopropane with excess hydrogen. The other primary processes are as follows in order of decreasing importance; cyclo-C3H6+hv→C2H3+CH3, 19% (18%), cyclo-C3H6+hv→C3H4+2H, 9% (7%), cyclo-C3H6+hv→C2H2+CH3+H, 3% (4%), cyclo-C3H6+hv→C2H2+CH4, 1% (1%).

Charge Distributions and Chemical Effects. IX. On the Charge Dependence of C-13 Chemical Shifts in Alkylcyclohexanes and Cyclopropane

Abstract: The analysis of ab initio charge distributions in cyclohexane and selected methylcyclohexanes indicates that no effect other than that described by the relationship δC = −237.1 qC + 242.64 between C-13 chemical shifts and C net charges (as determined for the alkanes) contributes to any significant extent to the shielding of the carbon atoms. This is no longer true for cyclopropane.