Dimethyl itaconate → HCID 9964174, compound

Participants

Reaction Conditions

Reaction Steps

The reaction was carried out in an Argonaut Endeavor hydrogenation vessel. The glass liner was charged with dimethyl itaconate (316 mg, 2.0 mmol) and 3,4-bis[(S,S)-2,5-diphenyl-phospholan-1-yl]-furan-2,5-dione-(1,5-cyclooctadiene) rhodium(I) tetrafluoroborate (1.7 mg, 0.002 mmol, S/C 1000). The vessel was charged to 10 bar nitrogen and vented (×5). Degassed methanol (4 ml) was added. The vessel was charged to 10 bar nitrogen and vented (×2). Stirring was commenced at 1000 rpm and the contents were heated to 25° C. The vessel was charged to 10 bar hydrogen. Hydrogen uptake was complete after 16 h. The mixture was vented and evaporated to give (S)-2-methylsuccinic acid dimethyl ester, conversion 100%, ee 96.6% (Chiraldex GTA, 30 m×0.25 mm, injector/detector 180° C., helium 14 psi, 90° C. for 6 min then ramp at 1° C./min to 105° C., retention times S 10.11 minutes, R 10.48 minutes). In comparison, much lower enantioselectivity, of 60.2% ee, is reported by Holz, J. et al, ibid., for the same transformation, at S/C 100 in methanol, catalysed by the corresponding rhodium complex of Me-Malphos [i.e. the analogue of ligand (7) with Me groups at the 2- and 5-position of each phospholane ring]. Holz, J. et al also report that a change of solvent, to THF, increases the enantioselectivity to 86% ee but this still falls short of the 96.6% ee achieved in the current example at a higher S/C ratio.

Provenance & Evidence