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

Abstract

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.

Angiogenesis-Inhibitory Piperidine Alkaloids from the Leaves of Microcos paniculata

“…16 Journal of Natural Products 4 Recently, Davies et al also finished the total synthesis of microgrewiapine A and O-acetyl microgrewiapine A and raised queries on their original assigned configurations. 5,6 In the present study, compound 11 was isolated with identical NMR spectroscopic data to microgrewiapine A. However, the optical rotation of 11 was measured as D 25 α [ ] = −22.8 (c 8.5, MeOH), which was also opposite to the natural microgrewiapine A.…”

Strategies for the discovery of potential anticancer agents from plants collected from Southeast Asian tropical rainforests as a case study

“…Consequently, it was pointed out that an error was made in our initial work in determining the optical rotation of this alkaloid. [50][51][52] Thus, the value originally published for microgrewiapine A {[a] 15 D +15.4 (c 0.1, MeOH)} 46 was corrected aer chemical synthesis to {[a] 20 D −16.0 (c 0.8, MeOH)}. 50 The availability of chemical synthesis routes should be useful in providing further quantities of microgrewiapine A (6) for more advanced biological studies than have been conducted to date.…”