1. Scriven, E. F. V. In Comprehensive Heterocyclic Chemistry; Katritzky, A. R.; Rees, C. W., Eds.; 1984; Vol. 2, p. 165.
2. (a) Carpino, L. A.; Mansour, E. M. E.; El-Faham, A. J. Org. Chem. 1993, 58, 4162.
3. (b) Carpino, L. A.; Beyermann, M.; Wenschuh, H.; Bienert, M. Acc. Chem. Res. 1996, 29, 268.
4. Full data of the X-ray crystal structure determination have been deposited with the Cambridge Crystallographic Data Centre, Cambridge, UK, as supplementary publication no. CCDC-145074.
5. Selected data for 4a: Colourless crystals, mp. 143–144°C; [α]D20=+159.5 (c 1, CH2Cl2); δH (300 MHz, CDCl3 J/Hz) 1.40 (d, J=7.2, 3H), 2.39 (s, 3H), 4.09 (q, J=7.0, 1H), 5.91 (s, 1H), 6.19 (d, J=7.5, 1H), 7.09–7.79 (m, 8H). δC (75 MHz, CDCl3) 20.54, 21.65, 57.53, 72.09, 116.45, 120.90, 124.76, 125.24, 128.08, 128.87, 128.98, 130.18, 130.46, 130.89, 132.28, 145.28, 168.77.