, 14a): yield 92%; (14b): yield 88%; (14d): yield 75%; (14e): yield 91%; (14f): yield 69% as a colourless oil. FT-IR (film) 3088, vol.848, pp.695-696, 0967.

, 69 (s, 1H), 6.60 (d, J = 1.3 Hz, 1H), 6.29 (s, 1H), 2.15 (s, 3H) ppm, Hz, 2H), 7.56 (d, J = 8.8 Hz, 2H), vol.6

, HRMS (ESI +ve) Exact mass calculated for C12H11NO5Na

, 15a): yield 53%; (15b): yield 83%; (15c): yield 95%; (15d): yield 80%; (15e): yield 95%; (15f): yield 81% as a colourless oil. FTIR (film), H NMR (400 MHz, CDCl3) ? = 9, vol.1, p.101, 1030.

. Mhz, Exact mass calculated for C9H12O5Na

, FT-IR (film) 3412, 2922, 1682, 1453, 958, 698 cm-1 ; 1 H NMR (400 MHz, CDCl3) ? = 9, Hydroxy(phenyl)methyl)acrylaldehyde (19): from compound (4a): yield 61% as a colourless oil, p.101

. Mhz, Exact mass calculated for C10H10O2Na

, )methyl) acrylaldehyde (20): from compound (6a): yield 78%; (6c): yield 86%; (6e): yield 86%; (6f): yield 93% as a colourless oil. FT-IR (film) 3071, vol.850, p.300, 1111.

. Mhz,

, from compound (11a): yield 81%; (11c): yield 53%; (11e): yield 63%; (11f): yield 74% as a colourless oil. FT-IR (film), vol.3458, pp.969-970, 1022.

, FT-IR (film) 2954, Methylene-5-oxo-5-(triethylsilyl)pentanal (22): from compound 5a: yield 60% as a colourless oil, vol.945, pp.719-720, 1016.

J. Hz-;-t, Dimethyl(phenyl)silyl)-2-methylene-5-oxopentanal (23): from compound 5b: 90% yield as a colourless oil. FT-IR (film), Hz, 2H), 0.96 (t, J = 8.0 Hz, 9H), 0.73 (q, J = 8.0 Hz, 6H) ppm; 13 C NMR (126 MHz, CDCl3) ? =, vol.815, pp.649-650, 0950.

J. Hz-;-t, Hz, 2H), 0.49 (s, 6H) ppm

, found: 269.0977. 2-Methylene-5-oxo-5-(triisopropylsilyl)pentanal (24): from compound 5d: yield 90% as a colourless oil. FT-IR (film) 2942, HRMS (ESI +ve) Exact mass calculated for C14H18O2NaSi, vol.828, p.300, 1251.

. Mhz, 93 (s, 1H), 2.68 (t, J = 7.1 Hz, 2H), 2.42 (t, J = 7.1 Hz, 2H), 1.28-1.14 (m, 3H), 1.02 (s, 9H), 0.98 (s, 9H) ppm, vol.5

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