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4‐Alkyl‐2,2,6,6‐tetramethyl‐1,4,2,6‐oxaazadisilinanes: synthesis, structure, and conformational analysis
Author(s) -
Lazareva Nataliya F.,
Shainyan Bagrat A.,
Kleinpeter Erich
Publication year - 2010
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1605
Subject(s) - conformational isomerism , chemistry , ring flip , alkyl , ring (chemistry) , molecule , stereochemistry , cyclohexane conformation , proton nmr , crystallography , organic chemistry , hydrogen bond
4‐Alkyl‐2,2,6,6‐tetramethyl‐1,4,2,6‐oxaazadisilinanes RN[CH 2 Si(Me) 2 ] 2 O [R = Me ( 1 ), i ‐Pr ( 2 )] were synthesized by two methods which provided good yields up to 84%. Low temperature NMR study of compounds ( 1 ) and ( 2 ) revealed a frozen ring inversion with the energy barriers of 8.5 and 7.7 kcal/mol at 163 and 143 K, respectively, which is substantially lower than that for their carbon analog, N ‐methylmorpholine. DFT calculations performed on the example of molecule ( 1 ) showed that NMe ax conformer to exist in the sofa conformation with the coplanar fragment CSiOSiC, and its NMe eq conformer in a flattened chair conformation. Copyright © 2009 John Wiley & Sons, Ltd.