15N chemical shifts of a series of isatin oxime ethers and their corresponding nitrone isomers.
In this article, we describe the characteristic (15)N chemical shifts of isatin oxime ethers and their isomer nitrone. These oxime ethers and nitrones are the alkylation reaction products of isatin oximes. In our study, the (15)N chemical shifts observed in these oxime ethers were in the 402-408 (or 22-28) ppm range, although those for their corresponding nitrone series were in the 280-320 (or -100 to -60) ppm range. This remarkable difference in (15)N NMR chemical shift values could potentially be used to determine the O- versus N-alkylation of oximes, even when only one isomer is available. In this paper, the differences in (15)N NMR chemical shifts serve as the basis for a discussion about how to distinguish both regioisomers derived from the oximes alkylation.
Liu
Xiaohong
X
Department of Drug Metabolism, Covance Company, 3301 Kinsman Boulevard, Madison, WI 53704, USA.
Huang
Xiaohua Stella
XS
Sin
Ny
N
Venables
Brian L
BL
Roongta
Vikram
V
D000478:Alkylation; D004583:Electrons; D004987:Ethers / Q000138:chemical synthesis / Q000737:chemistry*; D007510:Isatin / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D015394:Molecular Structure; D009587:Nitrogen Isotopes; D009589:Nitrogen Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D010091:Oximes / Q000138:chemical synthesis / Q000737:chemistry*; D012015:Reference Standards; D013237:Stereoisomerism
D004987:Ethers; D009587:Nitrogen Isotopes; D009589:Nitrogen Oxides; D010091:Oximes; C015388:nitrones; D007510:Isatin