Determining the predominant tautomeric structure of iodine-based group-transfer reagents by 17O NMR spectroscopy

Beilstein Journal of Organic Chemistry

Nico Santschi¹  Cody Ross Pitts¹  Benson J. Jelier¹  René Verel¹ 

[1] Eidgenössische Technische Hochschule (ETH) Zürich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 1/2, 8093 Zürich, Switzerland;

关键词: electrophilic;    hypervalent iodine;    17O NMR spectroscopy;    trifluoromethylation;    trifluoromethylthiolation;   

DOI  :  10.3762/bjoc.14.203

来源: DOAJ

【 摘 要 】

Cyclic benziodoxole systems have become a premier scaffold for the design of electrophilic transfer reagents. A particularly intriguing aspect is the fundamental II–IIII tautomerism about the hypervalent bond, which has led in certain cases to a surprising re-evaluation of the classic hypervalent structure. Thus, through a combination of 17O NMR spectroscopy at natural abundance with DFT calculations, we establish a convenient method to provide solution-phase structural insights for this class of ubiquitous reagents. In particular, we confirm that Shen’s revised, electrophilic SCF3-transfer reagent also adopts an "acyclic" thioperoxide tautomeric form in solution. After calibration, the approach described herein likely provides a more general and direct method to distinguish between cyclic and acyclic structural features based on a single experimental 17O NMR spectrum and a computationally-derived isotropic shift value. Furthermore, we apply this structural elucidation technique to predict the constitution of an electrophilic iodine-based cyano-transfer reagent as an NC–I–O motif and study the acid-mediated activation of Togni's trifluoromethylation reagent.

【 授权许可】

Unknown