Skeletal Rearrangements of Organoalkali Metal Compounds

Abstract

Dedicated to Professor Avery A. Morton on the occasion of his 85th birthdayOrganometallic compounds of the alkali metals undergo concerted [ 1 ,n] sigmatropic migration of aryl, vinyl, carbonyl, alkoxycarbonyl, silyl, germyl, and related groups. Sigmatropic migration of alkyl, benzyl, and hydrogen occur only under special circumstances and then may occur by an alternate fragmentation-recombination pathway. Ally1 groups may migrate by the latter process or by a concerted [2,3] sigmatropic reaction. These molecular rearrangements are discussed from the viewpoint of simple molecular orbital theory. By suitable choice of the alkali metal, temperature, ligands of the alkali cation and/or the solvent, considerable control may be exercised over the rate of rearrangement, the relative migratory aptitude of groups, and the mechanistic pathway.

Mechanistic studies of fluoride-promoted silicon elimination in β-benzotriazolyl-β-aryl-γ-ketosilanes

“…Intermediate 5 could arise from stabilization of the carbanion by a bridged phenonium anion perhaps via a Grovenstein-Zimmerman rearrangement. 4 Alternatively, formation of cyclopropyl species 7, formed by intramolecular addition of the primary anion to the carbonyl, can ring-open to carbanion 8 which is energetically favorable due to formation of carbonyl, double stabilized anion and release of three-membered ring strain. 5 While the Scheme 1 Rearrangement of 1 into the chalcone 9 upon vicinal elimination of trimethylsilyl and benzotriazolyl groups.…”

Chiral organometallic reagents. Part XXV.1 The stereochemistry of the ring opening of cyclopropylallyllithium compounds

“…This indicates that this ratio is kinetically controlled and does not arise from a rapid equilibration of E-and Z-20 via rapid reclosure to the cyclopropylallyllithium compound 19. 21…”

Theoretical Investigation of Stevens Rearrangement of P and As Ylides. Migration of H, CH3, CHCH2, SiH3, and GeH3Groups on P and As Atoms

“…The most common migrating groups in the [1,2] sigmatropic rearrangement of carbanions have an sp 2 carbon center such as acyl, phenyl, and vinyl groups. 33 The CHdCH 2 group was chosen as a model of such migrating groups. Also, it has been observed that the alkyl group such as the benzyl group migrates to a sufficiently negative center in the Stevens rearrangement, and thus we will compare the migrating aptitude between CHdCH 2 and CH 3 .…”

“…The most common migrating groups in the [1,2] sigmatropic rearrangement of carbanions have an sp 2 carbon center such as acyl, phenyl, and vinyl groups …”