Showing papers on "Double bond published in 1979"

Bonding Properties of Cyclopropane and Their Chemical Consequences

Abstract: Among the cyclic compounds of carbon, cyclopropane and its derivatives are outstanding by virtue of their unusual structural, spectroscopic, and chemical properties. The cyclopropane ring more closely resembles the CC double bond than the cyclobutane ring: it is a small ring with “double bond character”. Cyclopropyl and vinyl groups interact with neighbouring π-electron systems and p-electron centers; both cyclopropane derivatives and olefins form metal complexes, and add strong acids, halogens, and ozone; they both undergo catalytic hydrogenation and cycloadditions. While distinct differences in reactivity do exist–the double bond usually being more reactive than the three-membered ring–there are no fundamental differences in behavior.–Although cyclopropane derivatives have been known for more than 90 years, intensive studies have been limited to the past 25 years. The development of carbene chemistry has rendered cyclopropane derivatives far more readily accessible. In recent years, the synthetic potential of the small-ring function has been increasingly exploited. A considerable number of newly developed methods utilizing this approach clearly demonstrates that the reactivity of the cyclopropene ring, like that of the CC double bond, qualify it as a “functional carbon group”. This development is in full swing; we may therefore justifiably devote considerable effort to the study of cyclopropane chemistry.

Palladium Catalyzed Oxidation of Hydrocarbons

Abstract: I Introduction and Background- A General and Historical- B Inorganic Chemistry of Palladium- 1 Pd(0)- 2 Pd(I)- 3 Pd(II)- a Stable Compounds- b Equilibrium in Solution- (i) Aqueous Solution- (ii) Acetic Acid- (iii) Acetonitrile- (iv) Methanol and other Solvents- 4 Pd(IV)- C Organometallic Chemistry of Palladium- 1 Alkyls, Vinyls and Aryls- 2 Compounds of Palladium with Unsaturated Carbon Containing Ligands- a General- b Pd(0)- c Pd(I)- d Pd(II)- (i) Olefin ?-Complexes- (ii) ?-Acetylene Complexes- (iii) ?-Allyl Complexes- (iv) Cyclobutadiene and other C4 Systems- (v) Cyclopentadienyl Complexes- D The Two Basic Reactions of Catalysis and Examples of Each in Stable Palladium Organometallic Chemistry- 1 General- 2 The Oxidative Addition Reaction- 3 The Insertion Reaction- II Oxidation of Monoolefins- A General- B Formation of Aldehydes and Ketones- 1 Reaction Schemes- 2 Mechanism- a Effect of Ionic Strength- b Deuterium Labeling Experiments- c Kinetic Isotope Effects- d Ionic Strength Effects- e Exchange Studies- f Oxidation by Pd(II) Complexed to Di- and Triamines- C Production of Esters- 1 Introduction- 2 Oxidation in the Absence of Added Oxidants- 3 Oxidation in the Presence of other Oxidants- 4 Mechanism- a Unsaturated Ester Formation- b Saturated Ester Formation- D Production of Ethers and Acetals in Alcohols- 1 Reaction Schemes- 2 Mechanism- E Formation of Carbon-Carbon Bonds- 1 Introduction- 2 Olefin Arylation Reaction- a Reaction Schemes- b Mechanism- 3 Aliphatic and Olefinic Carbon-Carbon Bond Formation- a Addition of Pd(II)-Carbon Bonds across Olefinic Substrates- b Olefin Coupling Reaction- c Nonoxidative Dimerization- 4 Carbonylation Reaction with CO- F Formation of Carbon-Nitrogen Bonds- G Formation of Carbon-Halogen Bonds- H Formation of Carbon-Sulfur Bonds- I Formation of Carbon-Silicon Bonds- J Reaction of Monoolefins with (Ph3P)2PdO2- K Formation of Nitrates- III Reaction of Dienes and Polyenes- A Nonconjugated Dienes- 1 Stable Adducts- 2 Catalytic Reactions- B Conjugated Diolefins- 1 1,3-Diene Reactions- a Oxidation without Oligomerization- b Addition with Telomerization- c Cocyclization Reactions with Heteropolar Double Bonds- d Dimerization and Polymerization of 1,3-Dienes without Addition of Nucleophile- e Mechanisms of 1,3-Diene Reactions- 2 Reactions of 1,2-Dienes- IV ?-Allyl Complexes- A General- B Formation and Structure- C Reactions of ?-Allyl Complexes- 1 Aqueous Solutions- 2 Acetic Acid Solvent- 3 Formation of Carbon-Carbon Bonds- 4 Other Decomposition Reactions- V Reactions of Acetylenes- A General- B Oxidative Reactions- C Nonoxidative Reactions- VI Reactions of Aromatic Compounds- A Stable Palladium(II) Aryls- B Formation of Carbon-Oxygen Bonds: Aromatic Acetoxylation- C Formation of Carbon-Carbon Bonds- 1 Aromatic Coupling- 2 Carbonylation Reactions- 3 Miscellaneous Aromatic Carbon-Carbon Formation Reactions- D Formation of other Aromatic Bonds- E Mechanism of Aromatic Substitution Reactions- VII Miscellaneous Reactions- A Benzylic Oxidation- B Oxidative Dehydrogenation- C Reactions of Carbonyl-Containing Compounds- 1 Aldehydes and Ketones- 2 Quinone- 3 Carboxylic Acids and Acid Chlorides- D Reaction of C-O Bonds- 1 Alcohols- 2 Oxazines- 3 Hydroperoxides- 4 Lactones- 5 CO2- E Nitrogen-Containing Functional Groups- 1 Amines- 2 Nitro Compounds- 3 Reaction of Groups Containing ?C=N?- 4 Reactions of ?C?N Groups- 5 Miscellaneous N-Containing Groups- F Oxidation of Cyclopropanes- G Miscellaneous CO Reactions- H S and Si Containing Reactants- Indexes

The vibrational and electronic spectra of the mono‐, di‐, and trianon salts of TCNQ

Abstract: The vibrational and electronic spectra for the sodium mono‐, di‐, and trianion salts of TCNQ prepared in vacuo by solvent‐free vapor codeposition methods, have been measured. These data, combined with published vibrational assignments for neutral TCNQ and the monoanion salts of TCNQ, have permitted an empirical analysis of the effect of increasing electronic charge on the π‐ bonding of this conjugated system. Thus, empirical molecular force constants determined from new vibrational assignments, which are somewhat tentative in the case of the di‐ and trianion, indicate a regular transition of the p‐quinoid ring system of TCNQ0 to a benzenoid system for TCNQ3−. Simultaneously, the C≡N and C≡C bonds of the TCNQ wings are considerably reduced in strength while the wing C––C bonds gain double bond character eventually surpassing the original C=C bonds in strength in the case of TCNQ3−. The dianion salt, Na2TCNQ, is colorless while the trianion salt, Na3TCNQ, is golden yellow but there is little evidence in eit...

Totalsynthese von natürlichem α‐Tocopherol. 1. Mitteilung. Herstellung bifunktioneller, optisch aktiver Synthesebausteine für die Seitenkette mit Hilfe mikrobiologischer Umwandlungen

Abstract: Total Synthesis of Natural α-Tocopherol. I. Preparation of Bifunctional Optically Active Precursors for the Synthesis of the Side Chain by Means of Microbiological Transformations Our concept for a new total synthesis of natural α-tocopherol includes the synthesis of a corresponding (3 R, 7 R)-configurated C15 side chain to be built up by using twice an optically active C5 unit together with an achiral C5 end part. (S)-3-methyl-γ-butyrolactone (11) and (S)-2-methyl-γ-butyrolactone (9) represent suitable bifunctional C5-precursors for this purpose. These two key compounds have been prepared by fermentative transformation including the enantioselective hydrogenation of the double bond of ethyl-4, 4-dimethoxy-3-methylcrotonate (5) by bakers yeast (yielding 11 after ester hydrolysis and cyclization of the fermentation product) and (E)-3-(1′, 3′-dioxolan-2′-yl)-2-buten-1-ol (8) by the fungus Geotrichum candidum (yielding directly 9).

Pharmaceutically useful carbostyril derivatives

Abstract: Carbostyril derivatives having antihistamic action and central nervous controlling action are useful as antihistamic agents or central nervous controlling agents. The derivatives are represented by the general formula, ##STR1## wherein R 1 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkynyl group having 2 to 4 carbon atoms or a phenylalkyl group having an alkylene group containing 1 to 4 carbon atoms; R 2 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group; R 3 is a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkanolyoxy group having 1 to 4 carbon atoms or a 3,4,5-trimethoxybenzoyloxy group; R 4 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R 5 is a cycloalkyl group having 3 to 8 carbon atoms, a phenyl group (which may have 1 to 3 substituted groups selected from the group consisting of halogen atoms, alkyl groups having 1 to 4 carbon atoms and alkoxy groups having 1 to 4 carbon atoms), an alkyl group having 1 to 4 carbon atoms (having one substituted group such as a hydroxy group, a phenyl group or an alkanoyloxy group having 1 to 4 carbon atoms), an alkanoyl group having 1 to 4 carbon atoms or benzoyl group; X is a halogen atom; n is 0, or an integer of 1 or 2; Q is an integer of 2 or 3, l and m are respectively an integer of 0 or 1-6, but the sum of l and m should not exceed 6; the carbon-carbon bond at the 3- and 4-positions in the carbostyril skeleton is a single or double bond; and the substituted position of the side chain of ##STR2## is any one of the 4-, 5-, 6-, 7- or 8-positions.

Sugar derivatives of C-076 compounds, their preparation and their use as antiparasitic agents

Abstract: The invention provides derivatives of C-076, which is a series of macrolides, having certain hydrocarbon substituents. The hydrocarbon substituents in general are alkyl groups which may be straight or branched and may optionally be substituted with phenyl. The substituted C-076 compounds are prepared by various procedures depending upon the position of the reaction site, and the particular C-076 compound being substituted. The compounds thus produced are of formula: where the broken line indicates that a single or a double bond is present in the 22(23) position; R1 is hydroxy, loweralkanoyloxy or hydrocarbonoxy and is present only when the broken line indicates a single bond; R2 is iso-propyl or sec-butyl; R3 is hydrogen, methyl, loweralkanoyl or a hydrocarbon; R is hydrogen, loweralkanoyl, a hydrocarbon, where R. is hydrogen, loweralkanoyl or a hydrocarbon, and R5 is hydrogen or methyl; and the said hydrocarbonoxy group of R, is an alkoxy of from 1 to 10 carbon atoms or an alkoxy of from 1 to 10 carbon atoms or an alkoxy of from 1 to 10 carbon atoms substituted by phenyl and the said hydrocarbon groups of R and R4, which are the same or different, are alkyl of from 1 to 10 carbon atoms or alkyl of from 1 to 10 carbon atoms substituted by phenyl; and the said hydrocarbon group of R3 is an alkyl of from 2 to 10 carbon atoms or an alkyl of from 1 to 10 carbon atoms substituted by phenyl; provided that at least one of the R, R1, R3, and R4 groups is or contains a hydrocarbon group or R5 is methyl. They have profound anthelmintic, insecticidal, ectoparasiticidal and acaracidal activity and compositions for such uses are also disclosed.

Photopolymerizable compositions having combined photoinitiators

Abstract: In a photopolymerizable composition comprising (1) an addition-polymerizable compound having at least one ethylenically unsaturated double bond and (2) a photopolymerization initiator as essential components, the improvement which comprises that said photopolymerization initiator is a combination of (a) p-dialkylamino aromatic carbonyl compounds represented by the general formulae (1) to (4), (b) 5-isoxazolones represented by the general formula (5) and (c) 2,4,6-substituted-1,3,5-triazines represented by the general formula (6): ##STR1## where R 1 , R 2 and R 3 each represents an alkyl group or a substituted alkyl group, which may be the same or different from one another, X represents a substituent having a Hammett's σ value in the range from -0.9 to 0.7, m represents 1 or 2, A 1 and A 2 each represents an alkyl group, a substituted alkyl group, an alkylcarbonyl group, an alkoxycarbonyl group, an aryl group, a substituted aryl group, an arylcarbonyl group or a hydrogen atom, which may be the same or different from each other, and R 4 , R 5 and R 6 each represents an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group or an aralkyl group, which may be the same or different from each other, but at least one of them represents a mono-, di- or trihalomethyl group.

Conformation and Optical Activity of all‐trans, mono‐cis, and di‐cis Carotenoids: Temperature Dependent Circular Dichroism

Abstract: The CD. spectra of carotenoids with an asymmetric centre at C(3) have the following unusual features: (1) All-trans and di-cis compounds with two end-rings, at least one of which possesses an asymmetric C-atom, have very similar CD. spectra, whereas the corresponding mono-cis compounds give mirror-image CD. spectra; (2) In carotenoids or apocarotenoids with only one end-ring all-trans and mono-cis compounds have the same CD. spectra; (3) The CD. spectra of such carotenoids are strongly temperature dependent either increasing in magnitude or completely changing in sign upon cooling. These properties have been rationalized with the aid of a model with takes the total chromophore of the carotenoid as being intrinsically chiral with symmetry C2. It seems that the chirality arises not only from the presence of the hydroxyl group of an asymmetric carbon atom, C(3), which occupies an equatorial position thereby locking the conformation of the end-ring, but also from the steric hindrance across the formal single bond C(6), C(7), linking the end-ring to the chain and thus creating a chiral π-system. (The twist about the C(6), C(7)-bond acquires a handedness because of the predominance of one conformational form of the end-ring. In this way, the double bonds of the end-ring become twisted out of the plane of the chain with one hand predominating. Thus the whole conjugated system becomes chiral). The reversal of sign between the trans (and di-cis) and mono-cis compounds is due to a tilt of the 2-fold symmetry axis and thereby a change of chirality. The temperature dependence stems from the varying population of forms of different twist of the end-group relative to the chain. Compounds with 7, 8-triple bonds also show distinct CD. spectra and a sign change between all-trans and mono-cis isomers in addition to temperature dependence. The latter property demonstrates that some steric hindrance between the end-ring and the main chain is present in these compounds. Some suggestions for the origins of the sign patterns and band intensities of the CD. and absorption spectra are included.

Naturally occurring poly-cis carotenoids. Stereochemistry of poly-cis lycopene and its congeners in ‘Tangerine’ tomato fruits

Abstract: Spectroscopic data and comparison with synthetic model compounds establish that the carotenoid pigments phytoene, phytofluene, ζ-carotene, neurosporene, and lycopene found in the Tangerine tomato fruit have the sterochemistries C-15-mono-cis(1), C-15, C-9′-di-cis(2), C-9, C-9′-di-cis(3), C-9,C-9′,C-7′-tri-cis(4), and C-7,C-9,C-9′,C-7′-tetra-cis(5), respectively; the remaining double bonds in the pigments have the trans-geometry.

Cis‐trans double bond distribution in poly(1,3‐cyclopentylenevinylene); dependence on metathesis catalyst, cocatalyst, and additives

Abstract: About one hundred samples of poly(1,3-cyclopentylenevinylene) (2) were prepared by ring-opening polymerization of norbornene using a variety of metathesis catalysts based mainly on WCl6 or MoCl5, with EtAlCl2, BuLi, Ph4Sn, and (CH2CHCH2)4Sn as cocatalysts, and with methyl acrylate, diethyl maleate or diethyl fumarate as additives. Ir, Re, V, and Os compounds were also used as catalysts. The double bond pair sequences, trans-trans (tt), trans-cis (tc) etc. were determined from the 13C NMR spectra of these samples and the ratios rt(=tt/tc) and rc(=cc/ct) examined as a function of the fraction of double bonds σc having cis structure. For σc up to 0,35 all polymers showed random distribution of cis and trans structures (rtrc = 1), corresponding to a single type of propagating species. Polymers having σc = 0,35–0,85 invariably gave rtrc ≥ 1, with values greater than 5 in some cases. It is proposed that steric crowding of the active site leads both to high values of σc and to restriction of rotation about the metal-carbene bond of the propagating metalcarbene species, such as to give rise to kinetically distinct conformations which tend to regenerate their own kind on addition of monomer.

Crystal and Molecular Structure of Adenosine 5′-O-Phosphorothioate O-p-Nitrophenyl Ester (Sp Diastereomer)

Abstract: Phosphorylation of 2',3'-O-methoxymethylidene adenosine with bis(p-nitrophenyl) O,O-phosphorochloridothioate, followed by alkaline and acidic deprotection, afforded a mixture of the Rp and Sp diastereomers of adenosine 5'-O-phosphorothioate O-p-nitrophenyl ester in good yield. Only one of these diastereomers is a substrate for snake venom phosphodiesterase. The other diastereomer, remaining after complete enzymatic digestion of the substrate, was crystallized as the triethylammonium salt in the triclinic space group P1. The structure was solved from three-dimensional X-ray data and refined to an R value of 5.2%. The asymmetric cell unit contains two independent molecules with almost identical conformations. The ribose is puckered C(2')-endo, the heterocycle is in anti position and the C(5')-O(5') bond gauche, gauche. The triethylammonium cation is coordinated to the free oxygen of the phosphorothioate group and the P-S bond has double bond character. The absolute configuration of the phosphorous is Sp. This is in agreement with an earlier stereochemical study of the hydrolysis of the diastereomers of 5'-O-adenosyl 3'-O-uridyl phosphorothioate by snake venom phosphodiesterase.

Untersuchungen über die Autoxidation der isomeren n‐Octene

Abstract: Studies on the Autoxidation of the Isomeric n-Octenes The products of autoxidation of the positionally and sterically isomeric n-octenes were analyzed by gaschromatography. 22–37% of the gaschromatographically detected compounds were epoxides, 2–9% were products of oxidative cleavage of the CC-double bond, and 50–70% were allylic oxidation products. Independently of the stereochemistry of the starting olefins mixtures of the corresponding cis- and trans-epoxides were always formed; in the oxidation products of cisoctenes more cis-epoxides are present than in the oxidation products of trans-octenes. The composition of the octenol mixtures, obtained by preparative gaschromatographic isolation from the sodium sulphite reduction products of the oxidates, could be determined by 13C-n.m.r. analysis. All expected positional isomers are formed. The trans-octenes almost exclusively yield the trans-octenols; from the cis-octenes the octenols with the double bond in the original position are formed as mixtures of the corresponding cis- and trans-isomers, but the octenols with shifted double bonds almost exclusively are present in their transforms. The stereochemical results are discussed on the basis of the lifetime and the conformational or configurational stability of the intermediate radicals. In connection with the 13C-n.m.r.-investigation of the reaction products increments for the shift of 13C-signals by introduction of hydroperoxy, hydroxy, and carbonyl groups in allylic position of olefins were derived.