Bonding equations

The AMBER force field replaces the van der Waals by a 10-12 potential for pairs of atoms that can participate in hydrogen bonding (equation 12). The hydrogen bond potential does not contribute significantly to the hydrogen bonding attraction between two atoms rather, it is implemented to fine-tune the distances between these atoms. 

Reactions of the halogen iluorides with other unsaturated functional groups are generally reported only with highly fluorinated substrates Hexafluorobenzene and denvatives [118] and octaflvoronaphthalene [119] react with mixtures of bromine and bromine trifluoride by 1,4 addition of fluorine followed by addition of bromine fluoride across a reniatning double bond (equation 22)... 

Tnorganic and perfluoroorganic hypohalites add across olefimc bonds (equation 11 andTable 1) Thereactionsofhypofluontes have been included in a review on their chemistry [2J], In reactions of perfluoorganic hypofluontes, considerable fluonnation of the C=C bond may be observed With hypochlorites such as... 

Three-membered heterocyclic compounds are available when one atom fragments like carbenes [108 or phosphorus compounds [109] add to C=0 ot C=N bonds (equation 26)... 

Dehydrofluormation of A/,0-bis(tnfluoromethyl)hydroxylamine with potassium fluoride gives an excellent yield of a perfluorinated oxime ether [25] with a carhon-nitrogen double bond (equation 23)... 

Isomerization of fluoroolefins by a shift of a double bond is catalyzed by halide 10ns [7] The presence of crown ether makes this reaction more efficient [74] Prolonged reaction time favors the rearranged product with an internal double bond (equations 3-5) Isomerization of perfluoro-l-pentene with cesium fluoride yields perfluoro-2-pentenes in a Z ratio of 1 6 [75] Antimony pentafluoride also causes isomenzation of olefins leading to more substituted products [76]... 

A high endo selectivity is observed in the reaction of (phenylsulfonyl)allene (112) with furan (157) (equation 113)108. The endo adduct 158 can be readily transformed into highly substituted cyclohexenol 160 upon treatment with n-butyllithium after hydrogenation of the ring double bond (equation 114)108. 

Furthermore, to the extent that the nature of the activated complex of the catalytic step involving cleavage of the Pt=0 bond (equation 8.3) is not changing with varying O, one can use Polanyi s relationship,8 i.e. ... 

The classical Diels-Alder reaction is a cycloaddition between a conjugated diene and a second component, called dienophile, which has at least a n bond (Equation 1.1). When one or more heteroatoms are present in the diene and/or dienophile framework, the cycloaddition is called a hetero-Diels-Alder reaction. 

Some particular features should be mentioned. Instead of Michael additions, a-nitroolefins are reported to yield allyl sulfones under Pd catalysis (equation 21). Halogenated acceptor-olefins can substitute halogen P to the acceptor by ipso-substitution with sulfinate (equation 22 , equation 23 ) or can lose halogen a to the acceptor in the course of a secondary elimination occurring P to the introduced sulfonyl groups (equation 24). On the other hand, the use of hydrated sodium sulfinates can lead to cleavage at the C=C double bond (equation 25). 

Alkenylsiloxanes take part in cross-couplings as well. Hydrosilylation and cross-coupling can be combined in one pot to give an effective method of hydrocarbation of a triple bond (Equation (17)) 278... 

Electron transfer mechanism. In accord with the Mulliken theory, photoexcitation of the charge-transfer band effects the formation of a contact ion radical pair, which undergoes a rapid mesolytic scission of the M—H bond (equation 52). 

Regioselective N-difluoromethylation of 3-phenyl 1,2,4-triazole 39 has been achieved using chlorodifluoromethane in the presence of a base. The reaction yielded a mixture of the three possible products 40-42 and proceeds by the insertion of a difluorocarbene into an N-H bond (Equation 10) <1998JFC(92)141>. 

Palladocyclopentadiene reagent promotes [2 + 2]-cycloaddition of suitably positioned enynes to form cyclobutenes which undergo symmetry allowed ring opening to form 1,3-dienes with a bridgehead double bond (equation 149)264. 

Arenes can be transformed to fraws-disubsituted 1,2-dihydroarenes via temporary com-plexation with the electrophilic Cr(CO)3 group, followed by addition of a nucleophile and an electrophile across the arene double bond (equation 187)309. 

Allyl radicals can, of course, also be generated by electrolysis of the corresponding /J,y-unsaturated carboxylic acids together with a second carboxylic acid. This mixed Kolbe electrolysis method has been used to study the recombination of allyl radical 32 with the undecyl radical 3370. Recombination leads to the formation of adducts 34 and 35 in a ratio of 72 28, again preferring the product with the higher substituted double bond (equation 16). 

C-C bond formation can be favored over /3-hydride elimination by changing the nature of the catalyst. Hence, cyclizations can be mediated by iridium carbene complexes resulting from a formal intramolecular cross-coupling of the alkene with an. s -C-H bond (Equation (40)). 

Palladium-catalyzed directed intramolecular activations of aryl C-H bonds have been reported, as in the phenyla-tion of heterocycle analogs. Palladacycles are proposed intermediates, acting as effective catalysts, and the mechanism is likely to proceed via oxidation of Pd(ll) to Pd(iv) by the iodonium salt, as for the Equation (57), which described the activation of benzylic i/-CH bonds (Equations (121)—(123).109... 

In addition to coordination by heteroatoms, the 7r-bond of cyano group also participates the activation of C-H bonds (Equation (14)).14 The ruthenium-catalyzed alkylation of benzonitriles with triethylvinylsilane proceeds at the ortho-position predominantly. 

Addition of diselenide to allenes is efficiently catalyzed by Pd(PPh3)4. The addition occurs exclusively at the less substituted terminal C=C bond (Equation (79)).213 The addition to vinylidenecyclopropanes is catalyzed by iodosobenzene diacetate.214... 

In the reaction of an unsymmetrical diyne with 9, the boryl group is introduced regioselectively to the terminal acetylenic bond (Equation (100)). 

Facile 1,2-addition of the P-Se bond to alkynes occurs in a manner analogous to the addition of the P-S bond (Equation (131 )).299 High regio- and stereoselectivies are observed with phenylacetylene as well as aliphatic alkynes. 

The number of electrons in an ion may be checked using a formula for the calculation of unsaturation degree (rings-plus-double-bonds, Equation 5.7) ... 

Insertion into Si—I bond.1 Reaction of trimethylsilyl iodide or triflate with diazomethane results in insertion of a methylene group into the Si—I or Si—OTf bond (equation I). Similar insertion into (CH3)3SiBr requires ZnBr2 catalysis. 

The reaction of Ni(COD)2 with AlGp in benzene (Equation (68)) differs from that reported to take place in hexane which leads to unreactive Ni AlCp 4.47 Similarly, reactions in the presence of HSiEt3 result in oxidative addition across the Si-H bond (Equation (69))47 to produce a reactive complex that can be used for further chemistry (Equation (70)).47... 

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