Mechanism of the conversion of inverted CB[6] to CB[6]
SCIE
SCOPUS
- Title
- Mechanism of the conversion of inverted CB[6] to CB[6]
- Authors
- Liu, SM; Kim, K; Isaacs, L
- Date Issued
- 2007-08-31
- Publisher
- AMER CHEMICAL SOC
- Abstract
- Inverted cucurbit[n]urils (iCB[n]) form as intermediates during the synthesis of cucurbit[n]urils from glycoluril and formaldehyde in HCl (85 degrees C). Product resubmission experiments establish that the diastereomeric iCB[6] and iCB[7] are kinetic products that are less stable thermodynamically than CB[6] or CB[7] (> 2.8 kcal mol(-1)). When iCB[6] or iCB[7] is heated under aqueous acidic conditions, a preference for ring contraction is noted in the formation of CB[5] and CB[6], respectively. Interestingly, under anhydrous acidic conditions ring size is preserved with iCB[6] delivering CB[6] cleanly. To establish the intramolecular nature of the iCB[6] to CB[6] conversion under anhydrous, but not aqueous, acidic conditions we performed crossover experiments involving mixtures of iCB[6] and its (CO)-C-13 labeled isotopomer C-13(12)-iCB[6]. An unusual diastereomeric CB[6] with a Mobius geometry (13) is proposed as a mechanistic intermediate in the conversion of iCB[6] to CB[6] under anhydrous acidic conditions. The improved mechanistic understanding provided by this study suggests improved routes to CB[n]-type compounds.
- Keywords
- CHARGE-TRANSFER INTERACTIONS; BRIDGED GLYCOLURIL DIMERS; AQUEOUS-SOLUTION; DIASTEREOSELECTIVE FORMATION; CUCURBITURIL HOMOLOGS; MOLECULAR MACHINE; SYNTHETIC HOST; BINDING; RECOGNITION; DERIVATIVES
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/23210
- DOI
- 10.1021/JO071034T
- ISSN
- 0022-3263
- Article Type
- Article
- Citation
- JOURNAL OF ORGANIC CHEMISTRY, vol. 72, no. 18, page. 6840 - 6847, 2007-08-31
- Files in This Item:
- There are no files associated with this item.
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.