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1‐Methylphenanthro[3,4‐b]thiophene: Determination of the tertiary structure in solution and in the crystalline state by NMR spectroscopy and X‐ray diffraction
Author(s) -
Musmar M. J.,
Martin Gary E.,
Gampe Robert T.,
Lynch Vincent M.,
Simonsen Stanley H.,
Lee Milton L.,
Tedjamulia Marvin L.,
Castle Raymond N.
Publication year - 1985
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570220268
Subject(s) - chemistry , monoclinic crystal system , crystallography , heteronuclear molecule , intramolecular force , thiophene , molecule , nuclear overhauser effect , nuclear magnetic resonance spectroscopy , nmr spectra database , crystal structure , two dimensional nuclear magnetic resonance spectroscopy , spectroscopy , spectral line , x ray crystallography , crystal (programming language) , chemical shift , proton nmr , stereochemistry , diffraction , organic chemistry , programming language , physics , quantum mechanics , astronomy , computer science , optics
1‐Methylphenanthro[3,4‐ b ]thiophene was prepared by the photocyclization of 1‐(4′‐methyl‐2′‐thienyl)‐2‐(2″‐naphthyl)ethene. The 1 H and 13 C‐nmr spectra were assigned using two‐dimensional 1 H/ 13 C heteronuclear chemical shift correlation and relayed coherence transfer (RELAY) experiments. From nuclear Overhauser difference spectra, the H11‐C1 methyl‐H intramolecular distance was determined to be 2.10 Å. The molecule crystallized from chloroform in the monoclinic system, space group P2 1 /c. A total of 3536 unique reflections were measured and the structure was solved by direct methods and refined to a final R = 0.049. The molecule is helical with both chiral forms observed in the crystal. The H11‐C1 methyl‐H distance in the crystal was 2.12(3)Å in excellent agreement with the distance measured in solution by NOE techniques.