Furfural → (E)-3-(furan-2-ylmethylene)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)indolin-2-one

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Reaction Conditions

Reaction Steps

5-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)indolin-2-one (2.00 g, 7.7 mmol), ethyl alcohol (77 mL), piperidine (0.15 mL, 1.5 mmol), and 2-furaldehyde (0.77 mL, 9.3 mmol) were added to a 250 mL round-bottomed flask. The flask was sealed under a septum and heated to 80° C. for 5 hours. The mixture was cooled and filtered through a medium glass frit. The filtrate was adsorbed onto a plug of silica gel and chromatographed through a Redi-Sep® pre-packed silica gel column (120 g), eluting with a gradient of 0% to 70% EtOAc in hexane. The combined fractions were evaporated, and the product was crystallized out of EtOAc and hexanes at −20° C. to give (E)-3-(furan-2-ylmethylene)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)indolin-2-one (1.02 g, 39%) as an orange solid. LCMS (M+H) 338.1 calc. for C19H21BNO4338.1.

Provenance & Evidence