Premium
The Preparation of Optically Pure 7‐Oxabicyclo [2.2.1]hept‐2‐ene Derivatives. The CD Spectrum of (+)‐(1 R )‐7‐Oxabicyclo [2.2.1]hept‐5‐en‐2‐one
Author(s) -
Vieira Eric,
Vogel Pierre
Publication year - 1983
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19830660627
Subject(s) - chemistry , furan , saponification , ene reaction , adduct , toluene , yield (engineering) , absolute configuration , medicinal chemistry , crystallization , stereochemistry , nuclear chemistry , organic chemistry , materials science , metallurgy
(−)‐1‐Camphanoyloxyacrylonitrile (=(−)‐1‐cyanovinyl camphanate; 1 ) obtained from the commercially available (−)‐camphanoyl chloride and 2‐oxo‐propiononitrile added to furan at 20° in the presence of Cu (BF 4 ) 2 · 6H 2 O or ZnI 2 and gave a mixture of 2‐cyano‐7‐oxabicyclo [2.2.1]hept‐5‐en‐2‐yl camphanates ( 2–5 ) from which isomer 5 could be obtained pure by crystallization. The latter was transformed into (+)‐(1 R )‐7‐oxabicyclo[2.2.1]hept‐5‐en‐2‐one ( 6 ) in high yield and optical purity. Adducts 2–4 were recycled into 1 +furan by heating in toluene, and (−)‐camphanic acid was recovered after saponification of 5 . The absolute configuration of 6 was deduced from its CD spectrum which showed two 1200‐cm −1 Franck ‐ Condon series for its n→π CO *transition.