Reaktion #1277166

Reaktionsgleichung

3-amino-5-bromo-thiophene-2-carboxylic acid methyl ester

1,4-cyclohexanedione monoethylene ketal

phenyl silane

→

5-Bromo-3-(1,4-dioxa-spiro[4.5]dec-8-ylamino)-thiophene-2-carboxylic acid methyl ester

Ausbeute 92.0%

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   EinengenAfter concentration
2. 2
   workup.DISSOLUTIONthe residue was dissolved in EtOAc
3. 3
   Waschenwashed with NaHCO3
4. 4
   SonstigeThe organic layer was separated
5. 5
   Sonstigedried on Na2SO4
6. 6
   Filtrationfiltered
7. 7
   Einengenconcentrated
8. 8
   workup.ADDITIONThe crude material was diluted in hexane (500 ml)
9. 9
   FiltrationAfter filtration
10. 10
    Sonstigethe mother liquor was evaporated to dryness

Vorschrift

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).

Quelle