Ethyl vinyl ether → N-(6'-bromo-1'-(1-ethoxyvinyl)-4-methoxy-1',3'-dihydrospiro[cyclohexane-1,2'-indene]-1'-yl)-2-methylpropane-2-sulfinamide

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Reaction Conditions

Reaction Steps

To solution of ethyl vinyl ether (1) (269 mg, 357 μL, 3.73 mmol, 5 eq.) in dry THF (10 mL) chilled to −78° C. under N2 was added 1.7 M t-BuLi in heptanes (1.75 mL, 2.98 mmol, 4 eq.) dropwise within 10 min. The temperature of the resulting yellow clear solution1 was allowed to warm to 0° C. slowly within 30 min. By removing dry ice and adding water to dry ice-acetone bath, finally the cooling bath was replaced with a ice water bath. The color changed from yellow to nearly colorless after being stirred ca 5 min at 0° C. Then the lithium regent solution (2) was cooled to −78° C. again and cannulated to a solution of starting material 4 (307.5 mg, 0.746 mmol) in dry THF (5 mL) at −78° C. with positive pressure. The resulting mixture was stirred at this temperature for another 30 min. The reaction was quenched with saturated aqueous NH4Cl and extracted with ether and EA, the combined organic phases were washed with water and brine, dried, and filtered. The solvent was removed under reduced pressure to generate off-white foam, which was purified by flash chromatography on silica gel 9:1 eluted with EA in hexane (0-40%) to produce the desired product 5 and its diastereomers in a ratio (321 mg, yield 89%). MS ESI+ve m/z 484 (M+H)30.

Provenance & Evidence