Dimethyl Sulfoxide → HCID 10995440, compound

Participants

Reaction Conditions

Reaction Steps

Dimethyl sulfoxide (4.22 mL, 59.5 mmol, 15.0 equiv) was added to a solution of oxalyl chloride (3.46 mL, 39.7 mmol, 10.0 equiv) in dichloromethane (75 mL) at -78° C. After stirring at -78° C. for 20 min, a solution of allyl(6S,6aS,7S,10R,10aS)-2-(tert-butyldimethylsiloxy)-6-[(Z)-3-hexene-1,5-diynyl]-7,8,9,10-tetrahydro-10-hydroxy-9,9-dimethoxy-7-methyl-6a,10a-epoxyphenanthridine-5(6H)-carboxylate (23, 2.30 g, 3.97 mmol, 1 equiv) in dichloromethane (75 mL) was added over 10 min via cannula to the cold reaction solution. The reaction mixture was warmed to -40° C. and was held at that temperature for 10 h. The reaction mixture was then cooled to -78° C., triethylamine (16.6 mL, 119 mmol, 30.0 equiv) was added, and the resulting solution was stirred in an ice bath for 30 min. The product solution was poured into aqueous phosphate buffer solution (pH 7, 0.05M in sodium hydrogen phosphate and 0.05M in potassium dihydrogen phosphate, 150 mL). The aqueous layer was separated and extracted further with dichloromethane (2×150 mL). The combined organic layers were dried over sodium sulfate and were concentrated. The residue was purified by flash column chromatography (2% ethyl acetate-dichloromethane initially, grading to 5% ethyl acetate-dichloromethane) to afford allyl(6S,6aS,7S,10aR)-2-(tert-butyldimethylsiloxy)-6-[(Z)-3-hexene-1,5-diynyl]-7,8,9,10-tetrahydro-9,9-dimethoxy-7-methyl-10-oxo-6a,10a-epoxyphenanthridine-5(6H)-carboxylate (24) as a light brown foam (2.10 g, 92%). ##STR35##

Provenance & Evidence