Application of 1D BIRD or X-filtered DEPT long-range CC relay for detection of proton and carbon via four bonds and measuring long-range 13C13C coupling constants

✍ Scribed by Eri Fukushi; Jun Kawabata

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 144 KB
• Volume: 44
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1768

✦ Synopsis

We propose the 13 C-detecting 1D DEPT long-range C-C relay to detect super long-range H-C connectivity via four bonds ( 1 H-13 C-X-X-13 C, X represents 12 C or heteronuclear). It is derived from the DEPT C-C relay which detects the H-C correlations via two bonds ( 1 H-13 C-13 C) by setting the delays for J CC in the C-C relay sequence to the LR J CC . This sequence gives correlation signals split by small LR J CC , which seriously suffers from residual center signal. The unwanted signal is due to long-range C-H couplings ( LR J CH ). The expected relayed magnetization transfer 1 J CH → LR J CC occurs in the 1 H-13 C-X-(X)-13 C isotopomer, whereas the unwanted signal of LR J CH comes from 1 H-12 C-(X)-13 C isotopomers, whose population is 100 times larger than that of the 1 H-13 C-X-(X)-13 C isotopomer. The large dispersive line of this unwanted center signal would be a fatal problem in the case of detecting small LR J CC couplings. This central signal could be removed by an insertion of BIRD pulse or X-filter. DEPT spectrum editing solved a signal overlapping problem and enabled accurate determination of particular LR J CC values. We demonstrate here the examples of structure determination using connectivity between 1 H and 13 C via four bonds, and the application of long-range C-C coupling constants to discrimination of stereochemical assignments.