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Knoll W, Kaneno D, Bobek MM, et al. Intra- and intermolecular reaction selectivities of γ-substituted adamantanylidenes. J Org Chem. 2012;77(3):1340-60doi: 10.1021/jo202132c.
Knoll, W., Kaneno, D., Bobek, M. M., Brecker, L., Rosenberg, M. G., Tomoda, S., & Brinker, U. H. (2012). Intra- and intermolecular reaction selectivities of γ-substituted adamantanylidenes. The Journal of organic chemistry, 77(3), 1340-60. https://doi.org/10.1021/jo202132c
Knoll, Wolfgang, et al. "Intra- and intermolecular reaction selectivities of γ-substituted adamantanylidenes." The Journal of organic chemistry vol. 77,3 (2012): 1340-60. doi: https://doi.org/10.1021/jo202132c
Knoll W, Kaneno D, Bobek MM, Brecker L, Rosenberg MG, Tomoda S, Brinker UH. Intra- and intermolecular reaction selectivities of γ-substituted adamantanylidenes. J Org Chem. 2012 Feb 03;77(3):1340-60. doi: 10.1021/jo202132c. Epub 2012 Jan 12. PMID: 22168480.
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J Org Chem. 2012 Feb 03;77(3):1340-60. doi: 10.1021/jo202132c. Epub 2012 Jan 12.

Intra- and intermolecular reaction selectivities of γ-substituted adamantanylidenes.

The Journal of organic chemistry

Wolfgang Knoll, Daisuke Kaneno, Michael M Bobek, Lothar Brecker, Murray G Rosenberg, Shuji Tomoda, Udo H Brinker

Affiliations

  1. Physical Organic and Structural Chemistry, Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Austria.

PMID: 22168480 DOI: 10.1021/jo202132c

Abstract

A study of adamantanylidenes having a γ-substituent (R) was undertaken to gauge how inductive and steric effects of remotely positioned functional groups influence intra- and intermolecular product selectivity. 3H-Diazirines were thermolyzed or photolyzed to generate the corresponding carbenes. On rapid heating, the resulting carbenes isomerized to 2,4-didehydroadamantanes by intramolecular 1,3-CH insertions. When R was an electron donor (R(D)) mostly asymmetric 1-substituted derivatives were produced but when it was an electron acceptor (R(A)) the symmetric 7-substituted ones were formed. When solutions were exposed to UV-A light, intermolecular adducts from the carbenes and solvent predominated with lesser amounts of intramolecular product being formed. Valence isomerization of 3H-diazirines also afforded diazo compounds. In methanol, protonation of diazo compounds to give the corresponding 2-adamantyl cations exceeds their coupling. This diversion was controlled with fumaronitrile by trapping the diazo compounds. The adducts possessed mostly anti configurations with R = R(D) and syn arrangements with R = R(A). The connection between as- and anti-product formation and that of s- and syn-products was deemed to be the consequence of a rapid equilibrium between two distinct carbene conformations. This was qualified and quantified using ab initio calculations and NBO analyses.

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