1H and 13C nuclear magnetic resonance assignments and stereochemistry of N- n-butyl- N-methyl-11-(16′ α-chloro-3′,17′ β- and 17′ α-dihydroxyestrase-1′,3′,5′(10′)-trien-7′αyl undecanamide

Abstract

The stereochemistry of N-n-butyl-N-methyl-11-(16′α-chloro-3′,17′β-dihydroxyestra-1′,3′,5′(10′)-trien-7′α-yl) undecanamide ( 4) and N-n-butyl-N-methyl-11-(16′α-chloro-3′,17′α-dihydroxyestra-1′,3′,5′(10′)-trien-7′α-yl) undecanamide ( 5) at the 17′-position was unambiguously established by one dimensional nuclear Overhauser enhancement (NOE difference spectroscopy). Irradiation of H-18′ led to the increase in the signal of H-11′β, H-12′β, H-15′β, and H-16′β for compound 4 and a very small increase in the signal of H-17′ indicating the β-orientation of the 17′-OH. In contrast, for compound 5, the increase in the signal of H-17′ indicated the α-orientation of the 17′-hydroxy group. Complete assignment of the 1H and 13C resonances is facilitated by the following one- and two-dimensional NMR experiments: 1H homonuclear correlated spectroscopy (COSY), 1H- 13C heteronuclear shift correlation (HSC), 1H- 13C heteronuclear shift correlation via long range couplings (COLOC), and disoritionless enhancement by polarisation transfer (DEPT). Comparison of the 1H and 13C NMR chemical shifts indicated that the stereochemistry at the 17′ position is more easy to determine by analysing the chemical shifts of C-17′, C-12′, and C-18′. (Steroids 59:493–497, 1994)