Dimethylformamide → (Z)-2-Methoxy-3-{4-[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethoxy]-benzo[b]thiophen-7-yl}-acrylic Acid Methyl Ester

Participants

Reaction Conditions

Reaction Steps

A suspension of 6.39 g (15.9 mmol) of methyl 2-methoxy-2-(triphenylphosphonium)-acetate chloride (Prepared from methyl 2-chloro-2-methoxyacetate and triphenylphosphine, in analogy to: P. Seneci, I. Leger, M. Souchet, G. Nadler, Tetrahedron 1997, 53, 17097-17114), 0.68 g of lithium methylat (17.0 mmol) and 3.89 g of 4-[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethoxy]-benzo[b]thiophen-7-carbaldehyde (10.6 mmol) in 40 ml of DMF was heated for 23 h at 75° C. The light brown reaction solution was cooled to 0° C., the formed white crystals were filtered off, washed with 40 ml of methanol and dried to constant weight (20° C./1 mbar/16 h) to afford 3.54 g (73%) of the title compound with a purity of 97.5% (GC area; Method: column: DB-1 (15 m*0.32 mm); injector: 270° C.; detector: 320° C.; oven 150-310° C. (4° C./min); carrier gas: H2 (60 KPa). Retention times: starting material (aldehyde 1), 23.8 min; E-ester 5, 28.8 min; Z-ester 5, 30.8 min). m.p.: 165° C. MS: 450.3 (M+H)+. 1H-NMR (CDCl3): 2.40 (s, 3H); 3.08 (t, J=6.5, 2H); 3.78 (s, 3H); 3.88 (s, 3H); 4.45 (t, J=6.5, 2H); 6.86 (d, J=8.4, 1H); 7.21 (s, 1H); 7.34 (d, J=5.5, 1H); 7.38-7.45 (m, 3H); 7.49 (d, J=5.5, 1H); 7.95-8.00 (m, 2H); 8.10 (d, J=8.4, 1H).

Provenance & Evidence