Bis(2-bromoethyl) ether → 6-Bromo-2',3',5',6'-tetrahydrospiro[indene-2,4'-pyran]-1(3H)-one

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Reaction Steps

A solution of potassium tert-butoxide (3.94 g, 35.1 mmol) in t-BuOH (35 mL) was added dropwise over 15 min to a solution of 6-bromo-1-indanone (3.53 g, 16.73 mmol) in 2-methyl-tetrahydrofuran (350 mL) at r.t. under a nitrogen atmosphere. After 15 min bis(2-bromoethyl)ether (2.102 mL, 16.73 mmol) was added and the resulting mixture was stirred at r.t. for 5 h. Potassium tert-butoxide (0.938 g, 8.36 mmol) was added and the mixture was stirred at r.t. overnight. The mixture was quenched with saturated aq. NH4Cl (150 mL) and the organic layer was separated. The aqueous layer was extracted with EtOAc (3×50 mL) and Et2O (50 mL). The combined organics were washed with brine (100 mL), dried over MgSO4, filtered and concentrated. The resulting residue was taken up in DCM, concentrated onto silica gel and purified on a silica gel column eluted with 0-40% EtOAc in heptane to give 1.14 g (24% yield) of the title compound; MS (ES+) m/z 281 [M+H]1.

Provenance & Evidence