SENSITIVITY-ENHANCED DETECTION OF QUATERNARY CARMONS BASED ON CONTRIBUTION OF HETERONUCLEI AND ITS APPLICATION TO NATURAL PRODUCT ANALYSIS

本文提出了一种新的灵敏度增强的<13>C-C<13>观测方法--DEPT C-C中继。这一序列对于借助DEPT光谱编辑技术选择性地检测CH-C_q、CH_2-C_q和CH_3-C_q在季碳（c_q）上的连接性是有价值的。采用对称相位交替的复合脉冲，有效地补偿了高场仪器中随相位畸变而变化的谐振偏移量<13>。此外，由于来自^ CH的单量子相干的强贡献也经过了DEPT谱编辑的选择，因此，利用DEPT谱编辑构造CH、CH_2和CH_3子谱<13><13>，即使在质子化碳位点也能检测到^ C-^ C卫星信号<1j>，并且，利用^<1J>CH^<betaJ>CC或^<3J>CH^<betaJ>CC中继的上述方法的远程J版本也已实现。利用该方法，质子的磁化强度可以转移到离起始质子6个键远的碳原子上，并提出了一种新的ID ω_1异质半过滤CH相关方法PASS（pairing satellite selection）。通过后一种方法，可以精确测定长程JCH值，

A novel sensitivity-enhanced ^<13>C-^<13>C observation method, DEPT C-C relay, has been invented. This sequence is of value for selective detection of CH-C_q, CH_2-C_q and CH_3-C_q connectivities at quaternary carbons (c_q) with the aid of DEPT spectrum editing technique. The resonance-offset varying with phase distortion, which is especially a problem 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.Furthermore, a long-range J version of the above methos using ^<1J>CH^<betaJ>CC or ^<3J>CH^<betaJ>CC relay has also been accessible. By the method, magnetization of proton could be transferred to a remote carbon which locates six-bond away from the starting proton.Magnetization transfer through heteronuclear NOE and a novel ID omega_1 hetero half-filtered CH correlation method, PASS(paired satellite selection), have also been proposed. By the latter method, accurate determination of long-range ^JCH values has made possible