Olefin double-bond type

In order to locate items of interest in the book, the subject index lists, in addition to chemical operations, types of compounds rather than specific compounds (with a few exceptions). If, for example, readers do not find what they are looking for under the entry fluoroolefins , they may try olefins , double bonds, additions of , etc. 

Concerning nomenclature, fulvalene 2 and its related systems 1 and 3-6 are the parent structures of this class of heterocyclic cross-conjugated compounds. Both ring systems are numbered as shown in formula 9 (1,4,5,8-tetraazafulva-lene) beginning at the heteroatoms. Alternatively, as in the case of heptafulva-lene 10 (3,3 -diazaheptafulvalene), the numbers 1-7 and l -7 can be used.Tlie use of the name of the parent heterocycle connected by an olefinic double bond is often favored for the nomenclature of electron-rich olefines, for example, bis[3-(2,6-diisopropylphenyl)-4,5-dimethylthiazol-2-ylidene] for compound 51a (97LAR365). Similarly, azafulvalenes of type 11 and 12 can be re-... 

Recently, Meier et al. synthesized the most extended OP Vs (81) known to date [104]. Four different synthetic pathways were used for the generation of these OP Vs the final step involves the formation of one or two olefinic double bonds via a Wittig-Horner-type, a Siegrist-type or a McMurry-type condensation. 

Another approach was developed by Scott in the 1970 s (7.8) which utilises the same mechanochemistry used previously by Watson to initiate the Kharacsh-type addition of substituted alkyl mercaptans and disulphides to olefinic double bonds in unsaturated polymers. More recently, this approach was used to react a variety of additives (both antioxidants and modifiers) other than sulphur-containing compounds with saturated hydrocarbon polymers in the melt. In this method, mechanochemically formed alkyl radicals during the processing operation are utilised to produce polymer-bound functions which can either improve the additive performance and/or modify polymer properties (Al-Malaika, S., Quinn, N., and Scott, 6 Al-Malaika, S., Ibrahim, A., and Scott, 6., Aston University, Birmingham, unpublished work). This has provided a potential solution to the problem of loss of antioxidants by volatilisation or extraction since such antioxidants can only be removed by breaking chemical bonds. It can also provide substantial improvement to polymer properties, for example, in composites, under aggresive environments. 

The chemical reactions of sulphonyl nitrenes include hydrogen abstraction, insertion into aliphatic C—H bonds, aromatic substitution , addition to olefinic double bonds, trapping reactions with suitable nucleophiles, and Wolff-type rearrangement. Hydrogen-abstraction from saturated carbon atoms is usually considered to be a reaction typical of triplet... 

Introduction of a double bond between the triple bond and the leaving group leads to enyne electrophiles 45, which would give access to vinylallenes 46 if the attack of the nucleophile takes place at the triple bond in an SN2" (1,5) substitution reaction (Scheme 2.16). In addition to the regioselectivity, two types of stereoselectivity also have to be considered in this transformation, i.e. the configuration of the olefinic double bond of the vinylallene and the (relative or absolute) configuration of the allenic chirality axis. 

A great number of olefinic compounds are known to photodimerize in the crystalline state (1,2). Formation of a-truxillic and / -truxinic acids from two types of cinnamic acid crystals was interpreted by Bernstein and Quimby in 1943 to be a crystal lattice controlled reaction (5). In 1964 their hypothesis on cinnamic acid crystals was visualized by Schmidt and co-workers, who correlated the crystal structure of several olefin derivatives with photoreactivity and configuration of the products (4). In these olefinic crystals the potentially reactive double bonds are oriented in parallel to each other and are separated by approximately 4 A, favorable for [2+2] cycloaddition with minimal atomic and molecular motion. In general, the environment of olefinic double bonds in these crystals conforms to one of three principal types (a) the -type crystal, in which the double bonds of neighboring molecules make contact at a distance of -3.7 A across a center of symmetry to give a centrosymmetric dimer (1-dimer) (b) the / -type crystal, characterized by a lattice having one axial length of... 

In the pathway that we are proposing for the formation of organosele-nides, we also postulate the formation of a selenium (II) ester as the first step of the reaction. Further reaction of this ester with olefins followed by solvolysis will produce an intermediate alkylselenenic acid. Addition of this acid to an olefinic double bond will produce the type of selenide found in this system. 

Diazoalkanes, in particular diazomethane, can efficiently transfer a methylene unit to olefinic double bonds via a metal catalysed process. The range of alkenes that may be used as substrates in this cyclopropanation is vast. The efficiency of the cyclopropanation of various types of alkenes can be very dependent upon the particular catalyst chosen for the reaction. 

Aldehyde Formation. Several investigators observed a marked dominance of hexanal in the volatile products of low-temperature oxidation. At the higher temperatures, however, 2,4-decadienal was the major aldehyde formed (19,20,21). Both aldehydes are typical scission products of linoleate hydroperoxides. Swoboda and Lea (20) explained this difference on the basis of a selective further oxidation of the dienal at the higher temperature, while Kimoto and Gaddis (19) speculated that the carbon-carbon bond between the carbonyl group and the double bond (Type B) is the most vulnerable to cleavage under moderate conditions of autoxidation, while scission at the carbon-carbon bond away from the olefinic linkage (Type A) is favored under stress such as heat or alkali. 

Y. Yamamoto, S. G. Pyne, D. Schinzer, B. L. Feringa, J. F. G. A. Jansen, Formation of C-C Bonds by Reactions Involving Olefinic Double Bonds - Addition to a,/3-Unsaturated Carbonyl Compounds (Michael-Type Additions), in Methoden Org. Chem. (Houben-Weyl) 4th ed. 1952, Stereoselective Synthesis (G. Helmchen, R. W. Hoffmann, J. Mulzer, E. Schaumann, Eds.), Vol. E21b, 2041, Georg Thieme Verlag, Stuttgart, 1995. 

This type of photocyclization strategy has also been utilized [80] to construct indoline substructures 157 and 159 by irradiating enamine derivatives bearing an electron-withdrawing substituent on the olefinic double bond, such as 156. This was produced as a mixture of cis and trans diastereomeric indolines, as shown in Scheme 8.45. The formation of diastereomers (157 and 159) is explained by... 

Allylic organozinc reagents undergo addition reactions even across isolated (unconjugated) olefinic double bonds. Allylzinc bromide was reported to display both terminal and nonterminal addition reactions of this type (321, 323, 329). y-Ethylallylzinc bromide reacts with allylic... 

In addition to analogs incorporating an olefinic double bond as a linker between the macrolactone ring and different types of heterocycles, we have also studied a new family of side-chain modified structures, which are characterized by rigidifica-tion of the entire side-chain manifold (exemplified for quinoline-based analogs 30 and 31). ... 

Lahav et al. have obtained some oligomeric substances from ethyl-2-cyano-3 (p-sec.-butyl-3 -E-propenoate)-phenyl-E-propenoate-l which has two different types of photo-dimerizable olefinic double bonds within the same molecule9. ... 

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