Dimethylformamide → 5-Thia-1,8b-diazaacenaphthylene-4-carbaldehyde

To a solution of 7.777 g (38.076 mM) of 5-thia-1,8b-diazaacenaphthylene-4-methanol in ethyl acetate (50 ml)-N,N-dimethylformamide (50 ml) was added 23 g of active manganese dioxide and the mixture was stirred at room temperature for 4 hours. The reaction mixture was filtered and the precipitate was washed with N,N-dimethylformamide. The pooled filtrate was distilled under reduced pressure to remove the solvent. The crude 5-thia-1,8b-diazaacenaphthylene-4-carbaldehyde thus obtained was not purified but used as it was in the next reaction. To a solution of 9.39 g (41.9 mM) of ethyl diethylphosphonoacetate in 50 ml of toluene was added 1.68 g (41.9 mM) of a 60% suspension of sodium hydride in liquid paraffin at room temperature and the mixture was stirred for 0.5 hour. This mixture was added to a solution of the above crude 5-thia-1,8b-diazaacenaphthylene-4-carbaldehyde in N,N-dimethylformamide (50 ml)-toluene (200 ml) under ice cooling and the mixture was stirred at room temperature for one hour. This reaction mixture was poured in water and extracted with 3 portions of ethyl acetate. The organic layers were pooled and dried over MgSO4 and the solvent was distilled off under reduced pressure. The resulting crude ethyl 3-(5-thia-1,8b-diazaacenaphthylen-4-yl)acrylate was not purified but used as it was in the next reaction. To a solution of the above crude ethyl 3-(5-thia-1,8b-diazaacenaphthylen-4-yl)acrylate in 300 ml of ethanol was added 60 ml (120 mM) of 2N-aqueous solution of sodium hydroxide and the mixture was stirred at room temperature for 3 hours. To this reaction mixture was added concentrated hydrochloric acid (ca 10 ml) with stirring to bring the pH into the range of 4-5 and the resulting precipitate was recovered by filtration and rinsed serially with ethanol and diethyl ether to provide the title compound.

1. filtrationThe reaction mixture was filtered
2. washthe precipitate was washed with N,N-dimethylformamide
3. distillationThe pooled filtrate was distilled under reduced pressure
4. customto remove the solvent

ORD record

ord-059de76aaf8c491a83cb5af67914e434

Source dataset

uspto-grants-2001_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06235731B1