Application of 13C NMR Spectroscopy and 13C-Labeled Benzylammonium Salts to the Study of Rearrangements of Ammonium Benzylides

Tadeusz Zdrojewski , Andrzej Jończyk


Ylides generated from N-(cyanomethyl)-N,N-dimethyl-N-[α-(trimethylsilyl)benzyl]ammonium chloride (4) and fluoride anion afford the products of [1,2] shift 11 and [2,3] shift 13. Formation of product 13 shows that, in the presence of water from TBAF, rearrangements and [1,3]H shift in ylide intermediates become competitive processes. The reaction of N-benzyl-N,N-dimethyl-N-[α-(trimethylsilyl)benzyl]ammonium bromide (5) and 13C labeled (at the benzyl carbon) salt 5* gave a mixture of 10, 14, and 15 as products of [1,4], [1,2], and [2,3] rearrangement, respectively. 13C NMR spectra of products derived from salt 5* exclude [1,3]H shift in ylide 9a+-. Rearrangement of ylides generated from N-benzyl-N,N-dimethyl-N-[(dimethylphenylsilyl)methyl]ammonium bromide (6*) (enriched in 13C at benzyl carbon) and n-BuLi reveals that N,N-dimethyl-2-[(dimethylphenylsilyl)methyl]benzylamine (20*) is not formed by a [1,4] shift but instead, via a [2,3] shift in silylmethylide followed by subsequent [1,4]Si and [1,2]H shift, as previously suggested in the literature. This mechanism is unique to some silyl-substituted ylides.
Author Tadeusz Zdrojewski ZTiBSL
Tadeusz Zdrojewski,,
- Department Of Drug Technology And Biotechnology
, Andrzej Jończyk
Andrzej Jończyk,,
Journal seriesJournal of Organic Chemistry, ISSN 0022-3263
Issue year1998
Score (nominal)35
Publication indicators WoS Impact Factor: 2006 = 3.79 (2) - 2007=3.716 (5)
Citation count*11 (2015-03-10)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.