66835-10-7Relevant academic research and scientific papers
α-C-H Bond Functionalization of Unprotected Alicyclic Amines: Lewis-Acid-Promoted Addition of Enolates to Transient Imines
Kim, Jae Hyun,Paul, Anirudra,Ghiviriga, Ion,Seidel, Daniel
supporting information, p. 797 - 801 (2021/02/06)
Enolizable cyclic imines, obtained in situ from their corresponding lithium amides by oxidation with simple ketone oxidants, are readily alkylated with a range of enolates to provide mono- and polycyclic β-aminoketones in a single operation, including the natural product (±)-myrtine. Nitrile anions also serve as competent nucleophiles in these transformations, which are promoted by BF3 etherate. β-Aminoesters derived from ester enolates can be converted to the corresponding β-lactams.
Strategies for the Asymmetric Construction of Pelletierine and its Use in the Synthesis of Sedridine, Myrtine, and Lasubine
Zaidan, Raed K.,Evans, Paul
, p. 5354 - 5367 (2019/06/25)
Three methods for the asymmetric synthesis of both enantiomers of pelletierine 6 are reported. Bella's proline-based Mannich process gave (R)- and (S)-Cbz-protected 6 in good yields from Δ1-piperideine 14 and in reasonable enantiomeric excess (74–80 % ee). An intramolecular aza-Michael, cinchona-based, organocatalytic method is also reported. With commercially available 9-amino quinine (24a) and quinidine (24b) catalysts, Cbz-protected α,β-unsaturated ketone 23 also gave (R)- and (S)-Cbz-protected 6 in good yields and enantiomeric excess (90–99 % ee). This material was used to synthesize both optically active forms of deoxyhalofuginone (26), an analogue of febrifugine which is of interest as an anti-fibrotic agent. Finally, a resolution of racemic pelletierine using (R)- and (S)-mandelic acid 27 is reported. This scalable method gave both enantiomers of Cbz- and Boc-protected 6 in excellent enantiomeric excess (≥ 99 %). Both highly enantioenriched forms of 6 (obtained from the resolution study) were used to synthesize several alkaloids. Firstly, (–)-(S)-Cbz-protected pelletierine 17 was used to prepare naturally occurring sedridine (32) and its epimer allosedridine (8). Then the preparation of both enantiomers of the quinolizidine myrtine (33) by an olefination-intramolecular aza-Michael sequence is reported. Finally, the synthesis of the epimeric quinolizidine alkaloids, lasubine I (34) and lasubine II (35), from (+)- and (–)-Boc-protected pelletierine (29) respectively, is discussed.
