Heteronuclear single

HC HMQC (heteronuclear multiple quantum coherence) and HC HSQC (heteronuclear single quantum coherence) are the acronyms of the pulse sequences used for inverse carbon-proton shift correlations. These sensitive inverse experiments detect one-bond carbon-proton connectivities within some minutes instead of some hours as required for CH COSY as demonstrated by an HC HSQC experiment with a-pinene in Fig. 2.15. 

HSQC Heteronuclear single quantum coherence, e.g. inverse CH correlation via one-bond coupling providing the same result as HMQC but using an alternative pulse sequence... 

Conformations of mycothiol bimane (MSmB) were studied by H and 13C NMR using rotational nuclear Overhauser effect spectroscopy (ROESY) and heteronuclear single quantum correlation (HSQC) methods with expansions of the anomeric region <2003JOC3380>. NMR characterization of iV-acetyl-L-(Y)-cysteinyl monobimane and peracetylated MSmB was also published (Section 12.10.15.4) <2002JA3492>. 

No general studies have been carried out for these compounds, but there are several reports in which the stereochemistry of the final product has been elucidated by NOESY, correlation spectroscopy (COSY), or heteronuclear single quantum correlation (HSQC) experiments. For example, intensive NOESY experiments were used to establish the exact nature of each of the three cycloadducts 151a-c generated by the cycloaddition of a substituted nitrone to dimethyl (Z)-diethylenedicarboxylate <2000EJ03633>. 

Fig. 10.15. Pulse sequence for the multiplicity-edited gradient HSQC experiment. Heteronuclear single quantum coherence is created by the first INEPT step within the pulse sequence, followed by the evolution period, t . Following evolution, the heteronuclear single quantum coherence is reconverted to observable proton magnetization by the reverse INEPT step. The simultaneous 180° XH and 13C pulses flanked by the delays, A = l/2( 1 edits magnetization inverting signals for methylene resonances, while leaving methine and methyl signals with positive phase (Fig. 16A). Eliminating this pulse sequence element affords a heteronuclear shift correlation experiment in which all resonances have the same phase (Fig. 16B).

Exploitation of the TROSY effect is rather straightforward. In contrast to 15N-HSQC (Heteronuclear Single Quantum Coherence) or standard triple-resonance experiments based on 15N-HSQC, no radio frequency pulses or composite pulse decoupling should be applied on amide protons when HN spin is not in the transverse plane. Likewise the 15N decoupling should be... 

An extensive range of compounds with homonuclear or heteronuclear single or double bonds between As, Sb, or Bi is known. They include the simple tetraorganodimetallic species, R2MMR2, double bonded species RM=MR, linear tri- and tetra-metallated species, and mono- or polycyclic compounds. In addition, adducts with coordinative metal-metal bonds are known.44-46 463 Examples for cationic species with Sb-Sb bonds are Me2SbSbMe2+ and... 

A sequence suitable for measurement of J(H, P) and J(C, P) couplings is shown in Fig. 7.9a. The pulse sequence is a constant-time [13C, H]-HSQC (heteronuclear single-quantum correlation), in which 31P decoupling is applied in ot, in the first experiment and in co2 in the second. 

FHSQC fast heteronuclear single-quantum coherence... 

HSQC HMQC Heteronuclear single-quantum/multiple-quantum correlation spectroscopy To elucidate structure of organic molecules To determine heteronuclear coupling connectivity... 

HSQC Heteronuclear single-quantimi coherence NMR experiment... 

Fig. 10.3 Heteronuclear single quantum coherence (HSQC, panel a) and NMR...

FIGURE 2.1 heteronuclear single-quantum coherence spectrum of 5-carboxypyranocyanidin... 

Record the 2-D H-13C heteronuclear single quantum coherence (HSQC) spectrum (Braun et al., 1998, pp. 497-500). 

Furthermore, the allohimachalane (see Section 13.11.9.1) <1999T14623> as well as boletunones A and B, highly functionalized sesquiterpenes from the fruit body of the mushroom Boletus calopus <20040L823>, have been characterized by 2D-NMR (heteronuclear single quantum correlation (HSQC), HMBC, and 111-COSY). The structure of a drimen-ll,12-acetonide, isolated from Maya s herb, was deduced by means of 111 and 13C NMR, distortionless enhancement by polarization transfer (DEPT), COSY, NOESY, HSQC, and HMBC analyses <2005MRC339>. 

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