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Mechanistic Dichotomy in the Asymmetric Allylation of Aldehydes with Allyltrichlorosilanes Catalyzed by Chiral Pyridine N-Oxides

Andrei V. Malkov ; Sigitas Stoncius ; Mark Bell ; Fabiomassimo Castelluzzo ; Pedro Ramirez-Lopez ; Lada Biedermannova ; Vratislav Langer (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Lubomir Rulisek ; Pavel Kocovsky
Chemistry-a European Journal (0947-6539). Vol. 19 (2013), 28, p. 9167-9185.
[Artikel, refereegranskad vetenskaplig]

Detailed kinetic and computational investigation of the enantio- and diastereoselective allylation of aldehydes 1 with allyltrichlorosilanes 5, employing the pyridine N-oxides METHOX (9) and QUINOX (10) as chiral organocatalysts, indicate that the reaction can proceed through a dissociative (cationic) or associative (neutral) mechanism: METHOX apparently favors a pentacoordinate cationic transition state, while the less sterically demanding QUINOX is likely to operate via a hexacoordinate neutral complex. In both pathways, only one molecule of the catalyst is involved in the rate- and selectivity-determining step, which is supported by both experimental and computational data.

Nyckelord: allylation; allylsilanes; calculations; organocatalysis; pyridine N-oxides



Denna post skapades 2013-11-13.
CPL Pubid: 186544

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)

Ämnesområden

Kemi

Chalmers infrastruktur