918445-81-5Relevant articles and documents
Aiding factors in the formation of azaplatinacyclobutane rings - X-ray and crystal structure of [Pt{CH(Ph)CH2NEt2-KC,κN}(N,N, N′,N′-tetramethylethylenediamine)]+ and of its open-chain precursor
Lorusso, Giuseppe,Barone, Carmen R.,Di Masi, Nicola G.,Pacifico, Concetta,Maresca, Luciana,Natile, Giovanni
, p. 2144 - 2150 (2008/02/10)
The addition products 2 of a secondary amine to a coordinated olefin, in the cationic complexes [PtCl(η2-CH2=CHR)-(tmeda)] + (tmeda = N,N,N′,N′-tetramethylethylenediamine; R = Me, 1a; Ph, 1b, H, 1c), undergo in basic medium an intramolecular nucleophilic substitution with elimination of the chlorido ligand and formation of an azaplatinacyclobutane ring 3. The ring-closing process occurs notwithstanding the absence of a labilizing ligand trans to the leaving chlorido ligand and of bulky substituents on the amino-ethanide chain. If the addition product 2 is a mixture of Markovnikov and anti-Markovnikov isomers, the ring-closing reaction is faster for the anti-Markovnikov form, and this leads to an increase of the relative amount of the anti-Markovnikov isomer in the cyclized species 3. The difference in the rate of formation of the azaplatinacyclobutane ring between the two isomers has been interpreted on the basis of a more favorable stereochemistry in the case of the anti-Markovnikov form. The X-ray crystal structures of [Pt{CH(Ph)CH2NEt2-κC,κN}(tmeda)] + (3bn) and of its open-chain precursor, [PtCl{CH(Ph)CH 2NHEt2](tmeda)]+ (2bn) fully support this hypothesis. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
