Microgrewiapine C: Asymmetric Synthesis, Spectroscopic Data, and Configuration Assignment.

The first asymmetric synthesis of microgrewiapine C, a piperidine alkaloid isolated from Microcos paniculata , is reported. This synthesis prompted correction of the 1 H and 13 C NMR data for the natural sample of the alkaloid, which was achieved by reanalysis of the original spectra. The corrected data for the natural product were found to be identical to those of the synthetic sample prepared herein, thus confirming the structural and relative configurational assignment of microgrewiapine C. Although comparison of specific rotation values indicates that the (1 R ,2 S ,3 S ,6 S ) absolute configuration should be assigned to the alkaloid, consideration of potential common biosynthetic origins of microgrewiapine C and congeners suggests that further phytochemical investigations are warranted.