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Two-bond cleavage

Some fragmentations involve cleavage of two bonds simultaneously. In this process, an elimination occurs, and the odd-electron molecular ion yields an OE and an even-electron neutral fragment N, [Pg.449]

FIGURE 8.20 Representative inductive-cleavage fragmentations (Y = heteroatom). [Pg.449]

Copyright 2013 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duphcated, in whole or in part. [Pg.142]


A new domino lithium acetylide addition/rearrangement procedure on trans-1,2-dibenzoyl-3,5-cyclohexadiene furnished 3-alkylidene-2,3-dihydrofurans via an intriguing mechanism involving three bond formations and two bond cleavages in one single operation <06SL1230>. The reaction of dimedone with meso-diacetoxycyclohexene in the presence of a palladium catalyst led to the formation of the tricyclic product as depicted below <06S865>. [Pg.192]

Two bond cleavages convert bicyclobutane to a noncyclic species therefore, bicyclobutane is bicyclic. [Pg.49]

The two bond cleavages shown convert camphene to a noncychc species therefore, camphene is bicyclic. (Other pairs of bond cleavages are possible and lead to the same conclusion.)... [Pg.50]

Since czls-azoalkanes exhibit dipole moments of ca. (7... 10) 10 Cm (2... 3 D) [194], this solvent effect is best rationalized by assuming a decrease and final loss of the dipole moment during activation. Due to their dipole moments, czls-azoalkanes are more stabilized by polar solvents than the less dipolar activated complexes. The activation process corresponds to a synchronous, two-bond cleavage, probably accompanied by widening of the C—N=N bond angles [193]. A two-step, one-bond cleavage process via short-lived diazenyl radicals has been discussed [567], but this mechanism seems to be important only in the case of unsymmetrical azoalkanes, in particular arylazoalkanes [192]. [Pg.203]

The basic problems with which most investigations are concerned are the nature of the transition state, the variations of rate parameters with molecular structure and the question of whether the decomposition occurs in a step-wise manner or simultaneous two bond cleavage. [Pg.581]

The simultaneous two bond cleavage mechanism and the intermediacy of trimethylene was also substantiated by measurements of secondary deuterium isotope... [Pg.587]

Fragmentation of a l-silyloxybicyclo[/i.l.O]alkane with Pb(OAc)4 in acetic acid leads to two-bond cleavage to yield an alkenoic acid (Scheme 9). The reaction involves fission of the two bonds connected to the carbon bearing a silyloxy group. The reaction is considered to involve prior conversion of the silyloxycyclopropane to the corresponding cyclopropanol. In fact, treatment of a silyloxycyclopro-pane under strictly aprotic conditions gives a product due to one-bond cleavage (Scheme 9). [Pg.445]

A kinetic study of the thermal decomposition of 3-chloro-3-methoxydiazirine showed that the reaction was unimolecular both in the gas phase and in solu-tion. A direct two-bond cleavage to carbene was suggested for this reaction, without the formation of a diazo-compound. The authors suggest, however, that the decomposition of diazirine involves both pathways as competitive processes in the general case. [Pg.46]

It would be worthwhile to compare the behavior of bicyclo[ 1.1. OJbutane (XXIX) with that of the hydrocarbons described above. The smallest bicyclic hydrocarbon (XXIX) suffers two-bond cleavage by a nickel(O) catalyst to produce the allylcarbene-nickel(O) intermediate (XXX), which is trapped with coordinated olefins, giving the allylcyclopropane derivatives (XXXI) (Noyori et a ., 1971b, 1974d Noyori, 1973, 1975). The catalytic reaction of 3,3-... [Pg.96]

Some fragmentations involve cleavage of two bonds simultaneously. In this process, an elimination occurs, and the odd-electron molecular ion yields an OE and an even-electron neutral fragment N, usually a stable small molecule of some type H2O, a hydrogen halide, or an alkene. Some examples of two-bond cleavages of this type are shown in Figure 4.3. [Pg.142]


See other pages where Two-bond cleavage is mentioned: [Pg.311]    [Pg.768]    [Pg.145]    [Pg.900]    [Pg.900]    [Pg.133]    [Pg.43]    [Pg.43]    [Pg.53]    [Pg.669]    [Pg.110]    [Pg.579]    [Pg.768]    [Pg.669]    [Pg.768]    [Pg.181]    [Pg.317]    [Pg.321]    [Pg.145]    [Pg.181]    [Pg.700]    [Pg.11]    [Pg.117]    [Pg.6901]    [Pg.597]    [Pg.598]    [Pg.238]    [Pg.273]    [Pg.122]    [Pg.126]    [Pg.131]    [Pg.142]   
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With Cleavage of Two Te —C Bonds

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