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Cyclophanes, XLII. The Acid‐Catalyzed Isomerization of Perhydro[2.2]paracyclophane – A Surprising Out‐In Hydrogen Transfer Process
Author(s) -
Ernst Ludger,
Hopf Henning,
Savinsky Rainer
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970917
Subject(s) - chemistry , isomerization , dichloromethane , yield (engineering) , molecule , catalysis , hydrogen bond , computational chemistry , proton nmr , stereochemistry , photochemistry , organic chemistry , solvent , thermodynamics , physics
Treatment of perhydro[2.2]paracyclophane ( 1 ) with trifluoromethanesulfonic acid for 15 h at room temperature in dichloromethane results in a quantitative yield of stereoisomer 2 , in which one of the bridgehead hydrogen atoms points towards the inside of the molecule (mono‐ endo isomer). The constitution of 2 is derived from 2D‐NMR C,C‐INADE‐QUATE experiments and its stereochemistry from dynamic NMR experiments and molecular mechanics computations (MM3). A mechanism is suggested for the 1–2 interconversion.