Carbon‐13 and proton nuclear magnetic resonance studies of (E)‐ and (Z)‐ azetidinones

Abstract

Carbon‐13 and proton NMR spectra of a variety of E and Z pairs of mono‐ and bi‐cyclic polysubstituted azetidinones have been measured. The effect of E/Z isomerism on the chemical shift values of ring carbon atoms and of proton substituents attached to the azetidinone nucleus is discussed.

Trisoxazoline/Cu(II)‐Promoted Kinugasa Reaction. Enantioselective Synthesis of β‐Lactams.

“…56% yield (solid, 7 days); [α] 20 D -37.4 (c 0.66, CHCl 3 ; 85% ee);1 H NMR (300 MHz, CDCl 3 ): δ 7.45-7.41 (m, 2H), 7.33-7.26 (m, 2H), 7.22-7.19 (m, 5H),7.13-7.09 (m, 2H), 6.12-6.11 (m, 2H), 5.47 (d, J = 5.7 Hz, 1H), 4.97 (d, J = 6.0 Hz, 35% yield (solid,7 days); [α] 20 D -4.0 (c 0.80, CHCl 3 ; 84% ee); 1 H NMR (300 MHz, CDCl 3 ): δ 7.36 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 9.0 Hz, 2H), 7.17 (d, J = 8.1 Hz, 2H), 7.09-7.03 (m, 5H), 6.83 (d, J = 8.7 Hz, 2H), 5.47 d, J = 5.7 Hz, 1H), 5.04 (d, J = 6.0 Hz, 1H), 3.76 (s, 3H). 65% yield (solid, 40 h); [α] 20 D -6.5 (c 0.63, CHCl 3 ; 73% ee); 1 H NMR (300 MHz, CDCl 3 ): δ 7.42-7.30 (m, 6H), 7.20-7.05 (m, 8H), 5.51 (d, J = 6.0 Hz, 1H), 5.04 (d, J = 6.0 Hz, 1H); 13 C NMR (75 MHz, CDCl 3 ): δ 164.6, 137.4, 136.2, 133.8, 129.9 (q, 2 J C-F = 40), 129.1, 128.5, 128.3, 126.9, 125.0 (q, 3 J C-F = 3.6), 124.3, 123.9 (q, 1 J C-F = 256), 117.2, 60.0, 59.6; IR (KBr): 3038, 2924, 1749, 1736, 1599, 1500, 1382, 1322, 1167, 1125, 1069, 885, 819, 763, 702 cm -1 ; EI (m/z): 367 (M + ) (8), 181 (100); Anal.…”