P-64 NMRによる高感度C-C結合観測法とその応用(ポスター発表の部)

概要

論文の詳細を見る
A newly proposed DEPT C-C relay sequence is of value for selective and sensitive detection of CH-C_q, CH_2-C_q and CH_3-C_q connectivities at quaternary carbons (C_q) with the aid of a spectrum editing technique. The resonance-offset depending phase distortion, which is especially problematic in high field instruments, was efficiently compensated by using symmetric phase-alternating composite ^<13>C pulses. Moreover, construction of CH, CH_2 and CH_3 subspectra by DEPT spectrum editing made it possible to detect the ^<13>C-^<13>C satellite signals even at the protonated carbon sites since the strong contribution of the single quantum coherence derived from ^1J_<CH> also underwent the selection by the editing. By the method, three different J_<CC> values on quaternary carbons in a sesquiterpene, furanodienone (0.5mmol, 30min each), were separately detected and their accurate coupling constants could also be determined in each subspectrum. In addition, we present a 2D version of the sequence, DEPT C-C COSY, which enables well-resolved detection of C-C correlations, including those between protonated carbons. In the 2D sequence, the introduction of a second dimension would reduce signal overlapping, and hence, it becomes possible to detect C-C correlation peaks without the interference of unwanted residual signals. Spectral editing, as used in the corresponding 1D method, was no longer necessary for removing central residual signals since an optional baseline correction sufficiently suppressed undesirable F_1 ridges to give a clean 2D map. A sesquiterpene lactone, shizukanolide A (0.4mmol, 7hr), gave all C-C correlations except those starting from quaternary carbons and those between cyclopropyl carbons having extraordinarily small J values in the 2D sequence. Finally, long-range J_<CC> could also be detected in the 1D DEPT C-C relay including a BIRD pulse prior to the original sequence, which strictly removed the central unwanted signals in the CH subspectra.
天然有機化合物討論会の論文
1995-09-01

P-64 NMRによる高感度C-C結合観測法とその応用(ポスター発表の部)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク