Phenyl isocyanate → 4-[9-hydroxy-2-[5-[5-[6-hydroxy-3,5-dimethyl-6-(phenylcarbamoyloxymeth yl)oxan-2-yl]-3-methyl-oxolan-2-yl]-5-methyl-oxolan-2-yl]-2,8-dimethyl -1,6-dioxaspiro[4.5]dec-7-yl]-2-methyl-3-propanoyloxy-pentanoic acid

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Reaction Steps

Phenyl isocyanate (2.38 g, 20 mmol) was added to a solution of laidlomycin (14 g, 20 mmol) in 100 ml of pyridine. The mixture was heated in an oil bath at 70° for 30 min. The mixture was cooled, diluted with dichloromethane, washed with 5% aqueous hydrochloric acid and water, and evaporated. The residue was purified by silica gel chromatography (75% ether hexane, 0.01% formic acid eluent) to afford 10 g of laidlomycin phenylcarbamate as an amorphous solid which melted at 88°-90° C. Carbon-13 NMR spectroscopy confirmed the structure.

Provenance & Evidence