Correlated spectroscopy long-range experiment

COSY = homonuclear chemical shift correlation spectroscopy NOESY = 2D nuclear Overhauser effect (NOE) spectroscopy HMQC = heteronuclear mulltiple-quantum coherence RELAY = relayed coherence transfer COLOC = correlation via long-range coupling HMBC = heteronuclear long-range coupling INADEQUATE = incredible natural abundance double quantum transfer experiment. 

Heteronudear shift correlation spectroscopy is a 2D technique that can be used to determine the connectivity of H and C nuclei (or other heteronuclei), formally bonded together through one or more chemical bonds. The corresponding experiments make use of either the large or the smaller long-range "Jv, couplings for polarization transfer. 

There is a carbon detected analogue of the HMBC experiment called COLOC (Correlated spectroscopy for Long range Couplings) that predated the experiment treated here. The COLOC is not used much any more and we will not give any examples. 

COSY (correlation spectroscopy) is the first and the simplest 2D experiment. It correlates XH to XH via a single J coupling that may be two-bond (geminal), three-bond (vicinal), or in rare cases four-bond (long-range). Crosspeaks are antiphase in both F2 and F with respect to... 

The basic skeleton of casearin A (12) was elucidated by H-iH and H-correlated spectroscopy (COSY) and 2D-incredible natural abundance double quantum transfer experiment (INADEQUATE). The positions of ester functions were determined by the long range COSY... 

Another of the problems of N spectroscopy is the relative lack of chemical shift data it may well be the case that model data have to be generated to answer specific questions. References [78,79, 38], give some very useful shift data and references to other sources. Reference [80] gives an excellent introduction to the area, with a discussion of N referencing, N chemical shift ranges and practical experimental detail, in addition to a survey of long-range correlation experiments. 

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