Mechanisms for C(sp2)-Si activation of aryltrimethylsilyl groups in palladium-catalysed couplings.
Org Biomol Chem
; 15(38): 8179-8185, 2017 Oct 04.
Article
em En
| MEDLINE
| ID: mdl-28926074
ABSTRACT
Silyl-substituted aromatic compounds can participate as the electrophilic component in palladium-catalysed cross-couplings, and reactivity is enhanced by a neighbouring silyl-group. Products analogous to those obtained from C-H activation chemistry are accessible by this means with the additional benefit of regiochemistry defined by the site of silyl substitution. DFT studies described here show that the mechanism of C-Si cleavage is distinct from previously recognised mechanisms for C-H cleavage, with a cascade of silyl intermediates en route to a stable product. The amide directing-groups are involved only in the stabilisation of palladacyclic intermediates, and are never disposed to activate silicon directly. 5-Membered and 6-membered palladacycles are known to behave differently in coupling reactions and the calculations reveal underlying reasons in the cationic pathways studied here.
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MEDLINE
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En
Ano de publicação:
2017
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Article