Sodium Iodide → (+)-(5R)-5-Ethyl-5-hydroxy-2,5,6,9-tetrahydro-8-oxa-2-aza-benzocycloheptene-1,7-dione

Participants

Reaction Conditions

Reaction Steps

The residue obtained in Stage 83a is agitated for 16 hours at 20° C. in a mixture of dichloromethane (270 ml) and 1N hydrochloric acid (270 ml). After decanting, the organic phase is concentrated, and the residue is taken up in methanol (87 ml) to be used in the following phase. This solution is poured under nitrogen onto Palladium at 10% on damp carbon at 50% (27.7 g; 13 mmol). The reaction medium is agitated for 5 min, then poured into a solution of ammonium formate (11.5 g; 183 mmol) in methanol (135 ml). The reaction medium is agitated for 30 min whilst allowing the temperature to rise, then it is heated at 40° C. for 30 min. The medium is then filtered on a bed of Clarcel and concentrated. Toluene (40 ml) is poured in followed by evaporation, and this operation is repeated in order to eliminate the traces of methanol. The residue, taken up in tetrahydrofuran (45 ml), is treated with a solution of dicyclohexylcarbodiimide (7.18 g; 34.5 mmol) in tetrahydrofuran (20 ml). The reaction medium is heated at 50° C. for 1 hour, then taken to 20° C., and the dicyclohexylurea is filtered. The filtrate is concentrated to dryness and the residue, taken up in acetonitrile (46 ml), is treated with sodium iodide (6.0 g; 40.5 mmol) and trimethylsilyl chloride (5.13 ml; 40.5 mmol). The reaction medium is maintained under agitation at ambient temperature for 5 hours, then acetonitrile (28 ml) and water (5.6 ml) are added. The precipitate obtained is recovered by filtration, then taken up in water (10 ml), and the mixture obtained is neutralized using a solution of ammonium hydroxide. The precipitate is recovered by filtration then taken up in acetone (40 ml) to which water (150 ml) is added. The crystals formed are recovered by filtration and dried to produce 3 g of (+)-EHHOPD with an enantiomeric proportion of 99.4/0.6.

Provenance & Evidence