7291-07-8Relevant articles and documents
Rhodium-Catalyzed meta-Selective C?H Carboxylation Reaction of 1,1-Diarylethylenes via Hydrorhodation-Rhodium Migration
Caner, Joaquim,Iwasawa, Nobuharu,Saito, Takanobu,Toriumi, Naoyuki
supporting information, p. 23349 - 23356 (2021/09/18)
A meta-selective C?H carboxylation reaction of 1,1-diarylethylene derivatives with CO2 by using a rhodium catalyst with NaOiPr as a stoichiometric reductant has been achieved. Together with hydrogenation of the ethylene moiety, a carboxyl group was introduced to the meta-position of the aryl ring with high selectivity over the ortho-positions. Experimental and computational mechanistic studies indicate that this carboxylation reaction proceeds via hydrorhodation on the ethylene moiety, followed by 1,4-rhodium migration and successive 1,2-rhodium migration on the aryl ring. The use of a bulky phosphine ligand seems to be the key to this unusual aryl-to-aryl 1,2-rhodium shift.
A Study of Gaseous Benzenium and Toluenium Ions generated from 1,4-Dihydro- and 1-Methyl-1,4-dihydro-benzoic Acids
Kuck, Dietmar,Schneider, Jens,Gruetzmacher, Hans-Friedrich
, p. 689 - 696 (2007/10/02)
Gaseous benzenium C6H7(1+) (1) and toluenium C7H9(1+) (2) ions have been generated by mass spectrometric loss of .CO2H from the corresponding 1,4-dihydrobenzoic acids (3) and (4), and their fragmentations after ca. 10 μs have been investigated by means of mass-analysed ion kinetic energy (MIKE) spectrometry of some 2H and 13C labelled analogues.Metastable C6H7(1+) ions eliminate H2 after proton randomization, whereas metastable C7H9(1+) ions expel both H2 and CH4 after incomplete proton equilibration.In particular, 40percent of C7H9(1+) ions randomize all their carbon and hydrogen atoms prior to loss of CH4, and 60percent of C7H9(1+) ions lose the original methyl group along with a hydrogen atom from the (proton-equilibrated) benzenium ring, accompanied by a slow and incomplete exchange between the hydrogen atoms of the ring and the methyl group.It is suggested that loss of both CH4 and H2 occur via the (ipso-)toluenium ion (2).The role of a non-classical C7H9(1+) isomer, phenylmethonium ion (6), is discussed since striking similarities are found compared * adducts from ion-molecule reactions described in the literature.
