- 2-Substituted and 2,2-disubstituted adamantane derivatives as models for studying substituent chemical shifts and C-Hax?Yax cyclohexane contacts - results from experimental and theoretical NMR spectroscopic chemical shifts and DFT structures
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Abstract The complete 1H and 13C NMR chemical shifts assignment for various 2-substituted and 2,2-disubstituted adamantane derivatives 1-38 in CDCl3 solution was realized on the basis of NMR experiments combined with chemical structure information and DFT-GIAO (B3LYP/6-31+G(d,p)-GIAO) calculations of chemical shifts in solution. Substituent-induced 13C NMR chemical shifts (SCS) are discussed. C-Hax?Yax contacts are a textbook prototype of steric hindrance in organic chemistry. The nature of these contacts will be further investigated in this work on basis of new adamantane derivatives, which are substituted at C-2 to provide models for 1,4-C-Hax?Yax and 1,5-C-Hax?Yax contacts. The B3LYP/6-31+G(d,p) calculations predicted the presence of NBO hyperconjugative attractive interactions between C-Hax and Yax groups along C-Hax?Yax contacts. The 1H NMR signal separation, Δδ(γ-CH2), reflects the strength of the H-bonded C-Haxa?Yax contact.
- Kolocouris, Antonios,Koch, Andreas,Kleinpeter, Erich,Stylianakis, Ioannis
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- REACTION OF ORGANOMAGNESIUM COMPOUNDS OF THE ADAMANTANE SERIES WITH CARBONYL COMPOUNDS
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In the transformations of organomagnesium compounds of the adamantane series involving aldehydes, ketones, esters, and acid chlorides the nature of the reaction products and their yields are determined by the steric hindrances at the reaction centers of the organomagnesium and carbonyl compounds and by the ease of homolysis of the C-H bonds of the carbonyl reagent.The retardation of the faster addition of the Grignard reagent at the carbonyl group as a result of steric hindrances permits homolytic removal of a hydrogen atom from the carbonyl compounds by the adamantyl radical.
- Yurchenko, A. G.,Fedorenko, T. V.
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p. 875 - 880
(2007/10/02)
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