Reaction Steps
Compound 2f was prepared in an identical fashion to ester 2e by simply substituting the anion prepared from (tetraethyl)methylenediphosphonate for the Wittig reagent used above. The resulting vinyl phosphonate was then treated sequentially with TBAF·3H2O and PhCOCl as described in Example 7 to yield 2f: [α]22D =14.4° (c=0.355 g/100 mL, CHCl3); IR (thin film) 2958, 2931, 1714, 1452, 1315, 1275, 1114, 1051, 1026, 1798, 715 cm-1 ; 1H NMR (CDCl3) δ=1.09, 1.21 (each 3H, t, J=7.1 Hz, P(OEt)2), 1.65-1.70 (2H, m, H-6, H-7), 1.82-1.88 (1H, m), 1.99-2.12 (3H, m, H-6, H-7, H-4 ), 2.15 (3H, s, N-Me ), 2.83-2.88 (1H, m, H-2 ), 3.05-3.08 (1H, m, H-5), 3.22 (1H, br s, H-1), 2.72-4.00 (4H, m, P(OEt)2), 5.19 (1H, ddd, J=12.1, 6.8, 6.3 Hz, H-3), 5.59 (1H, dd, J=17.3, 21.6 Hz, =CH(P(OEt)2), 7.17 (1H, ddd, J=2.19, 17.3, 9.4 Hz, CH=CHP(O)(OEt)2), 7.32-7.51 (3H, m, Ar), 7.91-7.93 (2H, m, Ar); 13C NMR (CDCl3) δ16.17 (d, JC-P= 7.5 Hz), 25.05, 26.04, 29.58, 5.53, 41.11, 50.10 (d, JC-P= 22.1 Hz) 61.33, (d, JC-P =7.9 Hz), 66.57, 68.85, 118.33 (d, JC-P =184.7 Hz), 128.18, 29.47, 130.08, 132.86, 152.91, 165.67; MS (m/z) 407 (M+), 287, 286, 270 (base), 205, 148, 147, 123, 121, 105, 97, 94, 91, 83, 82, 81, 77, 76.
