[C:1]1([C@@H:7]2[C:11]([CH3:13])([CH3:12])[O:10][C:9](=[O:14])[NH:8]2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.C([Li])CCC.[C:20](Cl)(=[O:29])[CH:21]=[CH:22][C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1.C(OCC)(=O)C>O1CCCC1>[C:23]1(/[CH:22]=[CH:21]/[C:20]([N:8]2[C@H:7]([C:1]3[CH:2]=[CH:3][CH:4]=[CH:5][CH:6]=3)[C:11]([CH3:12])([CH3:13])[O:10][C:9]2=[O:14])=[O:29])[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1Reaction of the auxiliary (15) (0.300 g, 1.57 mmol) in solution in tetrahydrofuran (10 ml) at -78° C. with butyllithium (1.5M, 1.06 ml, 1.59 mmol) and cinnamoyl chloride (0.228 ml, 1.73 mmol) for 10 minutes and then at room temperature for 2 hours, with work-up and flash column chromatography using 20% ethyl acetate/40-60 petroleum ether as eluant furnished the title compound (26) as a solid (0.503 g, 99%) which was recrystallised from ethyl acetate/40-60 petroleum ether; mp 149° C.; νmax (CDCl3) 1682 and 1771 cm-1 ; [α]D26 (c 1 in CHCl3)=+26.0; (Found: C, 74.79; H, 5.94; N, 4.28. C20H19NO3 requires C, 74.75; H, 5.96; N, 4.36%); δH (CDCl3 ; 200 MHz) 1.04 (3H, s, C(CH3)2), 1.65 (3H, s, C(CH3)2), 5.24 (1H, s, CHPh), 7.20-7.64 (10H, m, ArCH), 7.80 (1H, d, J=15.8, CH=CHPh), 8.07 (1H, d, J=15.8, CH=CHPh); δC (125 MHz; CDCl3) 23.78 (CH3), 28.99 (CH3), 67.24 (CH), 82.47 (C), 117.17 (CH), 126.37 (CH), 128.48 (CH), 128.90 (CH), 130.70 (CH), 134.54 (C), 136.38 (C), 146.53 (CH), 153.33 (CO), 165.04 (CO); m/z (CI+, NH3) 322 (M+ +1)
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