Intra- and Intermolecular Reaction Selectivities of gamma-Substituted Adamantanylidenes

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

Publikation: Beitrag in FachzeitschriftArtikelBegutachtung

Abstract

A study of adamantanylidenes having a gamma-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.
OriginalspracheEnglisch
Seiten (von - bis)1340-1360
Seitenumfang21
FachzeitschriftJournal of Organic Chemistry
Volume77
Issue3
DOIs
PublikationsstatusVeröffentlicht - 2012

Research Field

  • Biosensor Technologies

Schlagwörter

  • O-H BOND; GOVERNING DIASTEREOFACIAL SELECTIVITY; HYDRIDE TRANSFER-REACTIONS; ALIPHATIC DIAZO-COMPOUNDS; ORBITAL EXTENSION MODEL; LASER FLASH-PHOTOLYSIS; FACIAL DIASTEREOSELECTION; CARBENE REARRANGEMENTS; CYCLISCHE DIAZOVERBINDUNGEN; 2-ADAMANTYL DERIVATIVE

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