71964-71-1Relevant academic research and scientific papers
Tests for Free-Radical Intermediates in the Decarbonylation of Aldehydes by Tris(triphenylphosphine)chlororhodium(I)
Kampmeier, J. A.,Harris, S. H.,Wedegaertner, D. K.
, p. 315 - 318 (2007/10/02)
Wilkinson's catalyst was reacted with phenylacetaldehyde (5h), phenylacetaldehyde-d (5d), p-methylphenylacetaldehyde (6), citronellal (7), and exo- and endo-5-norbornene-2-carboxaldehyde (10x and 10n).The decarbonylation of mixtures of 5h and 5d shows an isotope effect (kH/kD) of 1.86 +/- 0.07.No H-D crossover is observed when a mixture of 5d and 6 is reacted with 1.The reaction of citronellal (7) gives only 2,6-dimethyl-2-heptene. 10x gives norbornene, and 10n gives nortricycline; no crossover between the two systems is observed.These observations are consistent with concerted processes, intramolecular in aldehyde, for each step in the overall decarbonylation reaction; free- radical intermediates are excluded.
REARRANGEMENTS OF THE CARBANIONS DERIVED FROM ALLYL BENZYL THIOETHER
Biellmann, J. F.,Ducep, J. B.,Schirlin, D.
, p. 1249 - 1260 (2007/10/02)
The metalation of allyl benzyl thioether involves the benzylic or the allylic hydrogens.The benzylic carbanion undergoes a rapid sigmatropic shift whereas the allylic carbanion gives rise to various rearrangements, among them migration of the allylic unit to the para position with allylic inversion.The temperature dependence of the ratio of products arising from the benzylic carbanion vs those from the allylic carbanion shows that the allylic-to-benzylic carbanion transformation occurs only under special conditions: (a) with slow addition of the base; (b) with thioether in excess relative to the base, and (c) on raising the temperature of the reaction medium from -78 deg C to -15 deg C.In the last instance, the proton transfer is intramolecular as shown with labeled thioethers.The extent of the different rearrangements depends on the temperature and solvent.A choise of mechanism cannot be made at this time for the para migration 5-->9a.A leaving group effect on the reaction regioselectivity of the carbanion from allyl methyl thioether with benzyl halides has been noticed.The presence of dibenzyl indicates that, in addition to SN2 reactions, some electron transfer process is occuring.
