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Carbon‐13 spectral analysis, tautomeric structures and conformations of four two‐ring methylene‐bridged phloroglucinol derivatives
Author(s) -
Äyräs Pertti,
Lötjönen Simo,
Widén CarlJohan
Publication year - 1981
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270160309
Subject(s) - chemistry , phloroglucinol , ring (chemistry) , tautomer , methylene , stereochemistry , hydrogen bond , chemical shift , crystallography , molecule , medicinal chemistry , organic chemistry
Abstract The 13 C NMR spectra of phloropyron BB, desaspidin BB, albaspidin BB and margaspidin BB were recorded and the structures of the compounds investigated with the aid of chemical shifts and CH coupling constants. The filicinic acid ring of the first three compounds appeared to have a monoketonic structure with the carbonyl group in position 2 (acyl group in position 3). The pyronone ring of phloropyron BB also has a monoketonic structure, with the carbonyl function adjacent to the ring oxygen. The two rings of the first three compounds attain a conformation where a stabilizing hydrogen bond(s) is (are) formed between the two rings, as shown by the observed CH couplings to some of the hydroxyl protons. The spectrum of margaspidin BB, whichconsists of two aromatic acyl phloroglucinol rings, indicates less inter‐ring hydrogen bonding interactions.