Inversion of 1J(CC) correlations in 1,n-ADEQUATE spectra.
ADEQUATE experiments provide an alternative to the more commonly employed GHMBC experiment for the establishment of long-range heteronuclear connectivities. The 1,1-ADEQUATE experiment allows the unequivocal identification of both protonated and non-protonated carbon resonances adjacent to a protonated carbon. The 1,n-ADEQUATE experiment establishes correlations via an initial (1)J(CH) heteronuclear transfer followed by an (n)J(CC) out-and-back transfer, most typically, via three carbon-carbon bonds. Hence, the 1,n-ADEQUATE experiment allows the equivalent of (4)J(CH) heteronuclear correlations to be probed when they are not observed in a GHMBC spectrum. Aside from the lower sensitivity of the 1,n-ADEQUATE experiment relative to GHMBC experiments, the interpretation of the former is also complicated by the 'leakage' of (1)J(CC) correlations into the spectrum that must be identified. A method for the inversion of (1)J(CC) correlations to facilitate the interpretation of 1,n-ADEQUATE spectra is presented that allows a single experiment to be performed to access (1)J(CC) and (n)J(CC) correlation information.
Merck Research Laboratories, Discovery and Preclinical Sciences, Process and Analytical Chemistry, Structure Elucidation Group, Summit, NJ 07901, USA. gary.martin2@merck.com
Gary E
GE
Martin
R Thomas
RT
Williamson
Peter G
PG
Dormer
Wolfgang
W
Bermel
D002244:Carbon / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000592:standards*; D015394:Molecular Structure; D011522:Protons; D011763:Pyrrolizidine Alkaloids / Q000737:chemistry; D012015:Reference Standards
D011522:Protons; D011763:Pyrrolizidine Alkaloids; D002244:Carbon; C003300:retrorsine