Hydrochloric Acid → 6-bromo-3,4-dihydro-1H-2-benzopyran-1-one

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Reaction Steps

LDA (12 ml, 17 mmol) was dissolved in THF (50 ml) at −78° C. then 4-Bromo-2-methylbenzoic acid (1.0 g, 4.6 mmol) in 10 ml THF was added. The mixture was stirred for 10 minutes then paraformaldehyde (0.56 g, 18.6 mmol) was added. The reaction was stirred at RT for 4 hours. When LC-MS showed the product M+1=229, the reaction was poured into 1N HCl and extracted with ether. The organic layer was washed with brine, dried and evaporated to dryness. The residue was flashed through an Analogix 115 g column and eluted with 0-100% ethyl acetate/hexane to yield 6-bromo-3,4-dihydro-1H-isochromen-1-one.

Provenance & Evidence