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Magnetic Circular Dichroism Studies XXIII [1] Magnetic Circular Dichroism Spectra of Indole Alkaloids
Author(s) -
Barth Günter,
Linder Robert E.,
Bunnenberg Edward,
Djerassi Carl
Publication year - 1972
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.19720550637
Subject(s) - indole test , chemistry , chromophore , magnetic circular dichroism , circular dichroism , sign (mathematics) , crystallography , wavelength , spectral line , cotton effect , vibrational circular dichroism , oxindole , stereochemistry , photochemistry , optics , physics , organic chemistry , mathematical analysis , mathematics , astronomy , catalysis
The magnetic circular dichroism spectra of a number of indole alkaloids show two B‐terms of opposite sign in the 250–330 nm wavelength region associated with the 1 L b and 1 L a electronic transitions, the long wavelength, 1 L b , band being of positive sign, whereas both bands strongly overlap in absorption. Various substituents in different positions of the indole ring cause a red shift of both bands and a broadening of the long wavelength B‐term. The sign pattern, howver, remains unchanged in all examples thus far investigated. Dihydroindole and oxindole, on the other hand, exhibit MCD. bands with the opposite sign sequence as compared to the indole chromophore. This observation allows identification of the indole chromophore in alkaloids from the sign pattern of the MCD. bands.