(1-Ethoxy-3-morpholino-alkenylidene)pentacarbonylchromium complexes 1a-c react with terminal alkynes in DME to selectively give 4-ethoxy-5-(1'-morpholinoalkylidene)-2-cyclopentenones 3a,I and 3b,II and in THF/acetonitrile (9:1) to give 2-(1'-morpholinoalkenyl)-3-ethoxy-2-cyclopentenones 4a-c,I-IV in good to excellent yields (62-97%). Product 11b, an appropriately substituted derivative of 4, has been utilized in a short enantioselective synthesis of the tyrosine hydroxylase inhibiting natural product oudenone (13) from 1-pentynal (8).
- cyclopentenones, functionally substituted
- Fischer carbene complexes
- total synthesis