HSQC-ADEQUATE correlation: a new paradigm for establishing a molecular skeleton |
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Authors: | Martin Gary E Hilton Bruce D Blinov Kirill A |
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Institution: | Merck Research Laboratories, Discovery and Preclinical Sciences, Chemical Process Research, Rapid Structure Characterization Laboratory, Summit, NJ 07901, USA. gary.martin2@merck.com |
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Abstract: | Various experimental methods have been developed to unequivocally identify vicinal neighbor carbon atoms. Variants of the HMBC experiment intended for this purpose have included 2J3J-HMBC and H2BC. The 1,1-ADEQUATE experiment, in contrast, was developed to accomplish the same goal but relies on the (1) J(CC) coupling between a proton-carbon resonant pair and the adjacent neighbor carbon. Hence, 1,1-ADEQUATE can identify non-protonated adjacent neighbor carbons, whereas the 2J3J-HMBC and H2BC experiments require both neighbor carbons to be protonated to operate. Since 1,1-ADEQUATE data are normally interpreted with close reference to an HSQC spectrum of the molecule in question, we were interested in exploring the unsymmetrical indirect covariance processing of multiplicity-edited GHSQC and 1,1-ADEQUATE spectra to afford an HSQC-ADEQUATE correlation spectrum that facilitates the extraction of carbon-carbon connectivity information. The HSQC-ADEQUATE spectrum of strychnine is shown and the means by which the carbon skeleton can be conveniently traced is discussed. |
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Keywords: | HSQC 1 1‐ADEQUATE HSQC–ADEQUATE unsymmetrical indirect covariance generalized indirect covariance indirect covariance HMBC |
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