4,5-Dibromothiophene-2-carbaldehyde → cis-3-(4,5-Dibromo-thiophen-2-yl)-acrylic acid tert-butyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

(Diphenoxy-phosphoryl)-acetic acid tert-butyl ester (8.49 g, 24.4 mmol) was dissolved in THF (519 ml) and cooled to −78° C. followed by the addition of triton B (13.3 ml, 40% by wt. in MeOH). After 15 minutes a solution of 4,5-Dibromo-thiophene-2-carbaldehyde (7.0 g, 25.9 mmol) in THF (20 ml) was added and the reaction was stirred for 1 hour. Next, the reaction mixture was quenched with sat. NH4Cl (250 ml), diluted with H2O (500 ml), and extracted with EtOAc (2×300 ml). The organic layers were washed with water (2×200 ml), brine (100 ml), and dried (MgSO4). The crude was passed through a plug of silica gel with EtOAc providing the desired product 9.2 g (96%) as a 4:1 mixture of cis:trans. MS calculated for C10H12BrNS−H 367, observed M-tBu 309, 311, 313.

Herkunft & Nachweise