Premium
Electrocyclic Reactions of Siloles: A Combined Experimental and Theoretical Study
Author(s) -
MeyerWegner Frank,
Wender Josef H.,
Falahati Konstantin,
Porsch Timo,
Sinke Tanja,
Bolte Michael,
Wagner Matthias,
Holthausen Max C.,
Lerner HansWolfram
Publication year - 2014
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.201302544
Subject(s) - cyclopentadiene , cyclopentene , chemistry , cyclohexene , reactivity (psychology) , derivative (finance) , adduct , triclinic crystal system , medicinal chemistry , dimethyl acetylenedicarboxylate , cyclobutene , crystal structure , photochemistry , cycloaddition , ring (chemistry) , crystallography , organic chemistry , catalysis , medicine , alternative medicine , pathology , financial economics , economics
The reaction of 4‐chloro‐1,2‐dimethyl‐4‐supersilylsila‐1‐cyclopentene ( 2 a ) with Li[N i Pr 2 ] at −78 °C results in the formation of the formal 1,4‐addition product of the silacyclopentadiene derivative 3,4‐dimethyl‐1‐supersilylsila‐1,3‐cyclopentadiene ( 4 a ) with 2,3‐dimethyl‐4‐supersilylsila‐1,3‐cyclopentadiene ( 5 a ). In addition the respective adducts of the Diels–Alder reactions of 4 a + 4 a and 4 a + 5 a were obtained. Compound 4 a , which displays an s‐ cis ‐silacyclopentadiene configuration, reacts with cyclohexene to form the racemate of the [4+2] cycloadduct of 4 a and cyclohexene ( 9 ). In the reaction between 4 a and 2,3‐dimethylbutadiene, however, 4 a acted as silene as well as silacyclopentadiene to yield the [2+4] and [4+2] cycloadducts 10 and 11 , respectively. The constitutions of 9 , 10 , and 11 were confirmed by NMR spectroscopy and their crystal structures were determined. Reaction of 4‐chloro‐1,2‐dimethyl‐4‐ tert‐ butyl‐4‐silacyclopent‐1‐ene ( 2 c ) with KC 8 yielded the corresponding disilane ( 12 ), which was characterized by X‐ray crystal structure analysis (triclinic, P $\bar 1$ ). DFT calculations are used to unveil the mechanistic scenario underlying the observed reactivity.