Oxygen → HCID 11313290, compound

Participants

Reaction Steps

In the glove box (O2 content<=2 ppm) a 10 ml measuring flask was charged with 68.3 mg [Rh((R)-3,5-iPr-MeOBIPHEP)(COD)]SbF6 (0.050 mmol) and filled to the graduation mark with 10 ml ethyl acetate. The suspension was stirred with a magnetic stirring bar for 15 min at r.t. A clear orange solution formed. The Rh-catalyst was prepared through reaction of (R)-3,5-iPr-MeOBIPHEP and [Rh(COD)2]SbF6 in THF at room temperature for 2 h in a known manner (J. Am. Chem. Soc., 93, 3089-91 (1971), J. Chem. Soc. Chem. Comm., 1990, 869-71). In the glove box a 185 ml stirred stainless steel autoclave was charged with 16.02 g 3-(4-cyclopentylmethyl-5-oxo-2,5-dihydro-furan-3ylmethyl)-1,5,5-trimethyl-imidazolidine 2,4-dione, 20 ml ethyl acetate and the above catalyst solution. The measuring flask was rinsed with a total of 11.5 ml ethyl acetate. The autoclave was then sealed and connected to a hydrogenation line. The hydrogenation was carried out while stirring at 80° C. at a total pressure of 100 bar. After 71 h the brown hydrogenation mixture was rotary evaporated and dried at 50° C./10 mbar for 2 h, affording 16.80 g of crude (3R,4R)-3-(4-cyclopentylmethyl-5-oxo-tetrahydrofuran-3ylmethyl)-1,5,5-trimethyl-imidazolidine-2,4-dione as a brown oil which solidified slowly on standing at r.t. ee: 98.2% (3R,4R). GC:98.4 area %. This crude material was employed directly in the next step.

Provenance & Evidence