Nuclear Magnetic Resonance of Alkaloids

Abstract

This chapter describes the characteristic features of the Hydrogen-1(1H) and Carbon-13(13C) nuclear magnetic resonance (NMR) spectra of alkaloids with selected examples. The NMR spectra of some intermediates in the synthesis of a particular alkaloid and of selected alkaloid degradation products are described. Chemical shifts and coupling constants of many of the alkaloids and related systems are given with the structural formulae provide a reference collection of alkaloid NMR data. Many of the recorded proton–proton coupling constants are in fact splittings and are, therefore, only an approximation to the true coupling constants. 1H and 13C chemical shifts are in ppm to high frequency from internal tetramethylsilane (TMS) unless otherwise stated; coupling constants (or splittings) are in Hz. In the displays and tables of 13C NMR data, asterisks signify possible reversal of shift assignments. 13C assignments are made utilizing a variety of 1H decoupling methods, which are summarized. © 1978 Academic Press Inc. (London) Ltd.