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Autocorrelated 13 c‐ 13 c double quantum coherence two‐dimensional nmr spectroscopy: Utilization of a modified version of the technique as an adjunct in the total assignment of the 1 h‐ and 13 c‐nmr spectra of the mutagen phenanthro[3,4‐ b ]thiophene

1983; Wiley; Volume: 20; Issue: 6 Linguagem: Inglês

10.1002/jhet.5570200645

1943-5193

M. J. Musmar, M. Robert Willcott, Gary E. Martin, Robert T. Gampe, Masatomo Iwao, Milton L. Lee, Ralph E. Hurd, LeRoy F. Johnson, Raymond N. Castle,

Spectroscopy and Quantum Chemical Studies

Abstract Development of successively higher field nmr spectrometers has facilitated the study of increasingly more complex molecules, although smaller molecules such as phenanthro[3,4‐ b ]thiophene still offer very substantial assignment problems because of the highly congested nature of their 1 H‐ and 13 C‐nmr spectra. Assignments of such spectra, if they are to be unequivocal, frequently require the utilization of two‐dimensional nmr spectroscopic techniques. Total assignments of the 1 H‐ and 13 C‐nmr spectra of phenanthro[3,4‐ b ]thiophene are reported. Assignments were based on a conventional high resolution 500 MHz 1 H‐nmr spectrum, autocorrelated two‐dimensional 1 H‐nmr spectra (COSY), two‐dimensional 1 H‐ 13 C chemical shift correlation spectra and a modified version of autocorrelated 13 C‐ 13 C double quantum coherence two‐dimensional nmr spectroscopy. From NOE measurements, a separation of 1.99 Å between H1 and H11 was computed, suggesting that phenanthro[3,4‐ b ]thiophene has a pronounced helical conformation in solution.