COMPLETE H-1 AND C-13 NMR-SPECTRA OF 3-BE TA-HYDROXY-PREGN-5-EN-2O ONE AND ITS 2 DERIVATIVES

Assignments for signals from H-1 and C-13 in the NMR spectra of 3 beta -hydroxy-pregn-5-en-20-one (1), 3 beta-acetoxy-pregn-5-en-20-one (1a), and 3 beta-hydroxy-pregna-5,16-dien-20-one (2) were validated by two dimensional correlated spectroscopy (2D COSY) and heteronuclear single quantum coherence (HSQC). The narrow band of overlapping signals from H-7, H-2, and H-4 was resolved by exploiting three-bond coupling in t he 2D COSY spectra and heteronuclear correlation. Assignments were bas ed on high intensity cross peaks from long-range coupling by H-18 with H-17 and H-12 (axial). Similar cross peaks were observed for H-17 wit h H-21. Low intensity cross peaks were seen for H-4 coupled with H-6 a nd H-7, and also H-16 (quasi-axial) with H-14 of 1 and 1a. Assignments based on 2D COSY spectra were confirmed by correlation peaks from WSQ C. This now corrects the earlier conflicts among assignments reported for C-13 signals of 1 and 1a. Accurate assignments were similarly deri ved for signals from C-2, C-7, C-8, and C-21 of 1 and 1a, and C-15 and C-16 of 1, 1a, and 2. The complete sets of H-1 and C-13 NMR data for 3 beta-hydroxy-pregn-5-en-20-one (1), 3 beta-acetoxy-pregn-5-en-20-one (1a) and 3 beta-hydroxy-pregna-5,16-dien-20-one (2) serve as referenc e standards.