Triethylamine → Carbonic acid ethyl ester 8-methoxy-2-oxo-3-(2,4,6-trimethyl-phenyl)-1-thia-8-aza-spiro[4.5]dec-3-en-4-yl ester

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Reaction Steps

94 mg 4-Hydroxy-8-methoxy-3-(2,4,6-trimethyl-phenyl)-1-thia-8-aza-spiro[4.5]dec-3-en-2-one (from Step 7) and 43 mg triethylamine were dissolved in 10 ml tetrahydrofuran, and a solution of 32 mg ethyl chloroformate in 5 ml tetrahydrofuran was added dropwise. The mixture was stirred at ambient temperature for 18 hours, then partitioned between saturated aqueous sodium bicarbonate and t-butylmethyl ether, the organic layer dried over sodium sulfate, and the solvent evaporated. The residue was purified by chromatography on silica gel with ethylacetate/cyclohexane (1:2) as a solvent, to give 34 mg carbonic acid ethyl ester 8-methoxy-2-oxo-3-(2,4,6-trimethyl-phenyl)-1-thia-8-aza-spiro[4.5]dec-3-en-4-yl ester (title compound P1.7) as a solid, mp 87-89° C.

Provenance & Evidence