Benzyl group migration

Allyl allylacetate is obtained in 43% yield. The dibenzylacetal also rearranges, but the migrating benzyl group appe ars as an o-tolyl group, the product being benzyl o-tolylacetate. 

From a phosphorothioate TFMSA, m-cresol, thiophenol, TFA. These conditions minimized the migration of the benzyl group to the thione. ... 

In the case of elimination from (9), isoindole formation competes with 1,2-migration of the benzyl group (Stevens rearrtingement ), whichgives l-benzyl-2-m6thylisoindoline (10), and also with migration... 

Nano- and microsecond laser flash spectroscopy was employed to clarify photophysical effects on benzyl group migration in 2//-thiopyran 60 (R = PhCH2, 86MI1). 

Bz)Co(emg2tn)(OH2)]+ has been shown to perform an unusual Co-to-C migration of the axial alkyl group upon photolysis, with the benzyl group attacking one of the oxime C atoms.1167... 

The last reaction shows that the benzyl group has a superior migration aptitude in the Stevens rearrangement. It is more reactive in nucleophilic... 

Various mechanisms are discussed for the migration of a benzyl group including, e.g., a two-stage Cope or reverse Claisen rearrangement as well as a preference of direct [l,5]-shift over successive Wagner-Meerwein migrations (equation 115)173. 

The thermally induced cyclization of A -(benzyloxycarbonyl)phenyl ketenimines 415, obtained in a two-step, one-pot procedure from benzyl 2-azidobenzoates 414, led to 2-substituted-4/f-3,l-benzoxazin-4-ones 416 (Scheme 79). The reaction involves the formation of a new carbon-oxygen bond and migration of the benzyl group from the oxygen atom to the terminal carbon atom of the ketenimine fragment <2005S2426>. 

Ammonium ylides undergo [l,2]-shift in a manner similar to oxonium and sulfonium ylides. A preferentially migrating group is usually a benzyl group. A sequence of intramolecular formation of ammonium ylide and subsequent rearrangement was extensively explored by West and co-workers in the synthesis of cyclic amines. ... 

Compound 21 is formed upon reaction of Bu2Mg with a silyl hydrazine (Scheme 4). In this instance the base removes a proton from the hydrazine followed by an unexpected migration of the benzyl group, and subsequent deprotonation of the trimethylsilyl... 

The 1,3-migration of the 4-benzyl group of 4-benzyl-2,4,5,6-triphenyl-4//-pyran (621) was accompanied by photodehydrogenation of 5,6-substituents (Eq. 46).400... 

Migration of a benzyl group appears to occur in preference to hydrogen, alkyl, or aryl migration, as with 1,3-diphenyl-2-methyl-1,2- Toxypropane (Eq. 461), which yields 3,4-diphenyl-2-butanone -elusively.1024-102 Of some interest, incidentally, is the report that... 

The reactions described so far all yield medium-ring tertiary amines. Reinecke s group have recently extended their methods to synthesize the more useful secondary amines.288 Three syntheses were developed. The first [Eq. (31)] involves reductive cleavage of the benzyl indolizidinium salt 229 with lithium aluminum hydride, followed by replacement of the benzyl group with the labile trichloroethoxycarbonyl group. The latter may be removed under mild conditions with zinc-methanol, which does not cause migration of the double bond. 

---