反应详情

A suspension of 3-amino-5-bromo-thiophene-2-carboxylic acid methyl ester (17.0 g, 72.0 mmol) in dry THF (21 ml) was treated with 1,4-cyclohexanedione monoethylene ketal (11.3 mg, 72.0 mmol), followed by dibutyltin dichloride (1.098 gr, 3.6 mmol). After 5 min, phenyl silane (9.74 ml, 79.2 mmol) was added and the reaction mixture was stirred overnight at room temperature. After concentration, the residue was dissolved in EtOAc washed with NaHCO3 then brine. The organic layer was separated, dried on Na2SO4, filtered and concentrated. The crude material was diluted in hexane (500 ml). After filtration, the mother liquor was evaporated to dryness to give 5-Bromo-3-(1,4-dioxa-spiro[4.5]dec-8-ylamino)-thiophene-2-carboxylic acid methyl ester (24.79 g, 92% yield). 1H NMR (CDCl3, 400 MHz): 6.90 (br s, 1H), 6.65 (s, 1H), 3.95 (s, 4H), 3.78 (s, 3H), 3.35 (m, 1H), 2.00 (m, 2H), 1.80 (m, 2H), 1.65 (m, 4H).

1. concentrationAfter concentration
2. dissolutionthe residue was dissolved in EtOAc
3. washwashed with NaHCO3
4. customThe organic layer was separated
5. customdried on Na2SO4
6. filtrationfiltered
7. concentrationconcentrated
8. additionThe crude material was diluted in hexane (500 ml)
9. filtrationAfter filtration
10. customthe mother liquor was evaporated to dryness