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Reaction of an N‐Heterocyclic Carbene‐Stabilized Silicon(II) Monohydride with Alkynes: [2+2+1] Cycloaddition versus Hydrogen Abstraction
Author(s) -
Eisenhut Carsten,
Szilvási Tibor,
Breit Nora C.,
Inoue Shigeyoshi
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405303
Subject(s) - phenylacetylene , silylene , diphenylacetylene , carbene , chemistry , reactivity (psychology) , cycloaddition , medicinal chemistry , hydrogen atom abstraction , density functional theory , photochemistry , computational chemistry , hydrogen , silicon , catalysis , organic chemistry , medicine , alternative medicine , pathology
An in depth study of the reactivity of an N‐heterocyclic carbene (NHC)‐stabilized silylene monohydride with alkynes is reported. The reaction of silylene monohydride 1 , t Bu 3 Si(H)Si←NHC, with diphenylacetylene afforded silole 2 , t Bu 3 Si(H)Si(C 4 Ph 4 ). The density functional theory (DFT) calculations for the reaction mechanism of the [2+2+1] cycloaddition revealed that the NHC played a major part stabilizing zwitterionic transition states and intermediates to assist the cyclization pathway. A significantly different outcome was observed, when silylene monohydride 1 was treated with phenylacetylene, which gave rise to supersilyl substituted 1‐alkenyl‐1‐alkynylsilane 3 , t Bu 3 Si(H)Si(CHCHPh)(CCPh). Mechanistic investigations using an isotope labelling technique and DFT calculations suggest that this reaction occurs through a similar zwitterionic intermediate and subsequent hydrogen abstraction from a second molecule of phenylacetylene.