501-83-7Relevant articles and documents
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.
Stereocontrol in N-directed hydroboration: Synthesis of amino alcohols related to the piperidine alkaloids
Wang, Guoqiang,Vedejs, Edwin
supporting information; experimental part, p. 1059 - 1061 (2009/08/15)
Treatment of 2-(2'-alkenyl)-piperidine boranes with iodine or triflic acid induces internal hydroboration with high regiocontrol, even with a terminal alkene (R H). Good stereocontrol is possible for the N-benzyl substrates. Comparisons with acyclic model
The Regiochemistry and Stereochemistry of 1,3-Dipolar Cycloaddition of a Cyclic Nitrone
Ali, Sk. Asrof,Wazeer, Mohammed I. M.
, p. 597 - 606 (2007/10/02)
A study of the regiochemical and stereochemical behaviour of the 1,3-dipolar cycloaddition of a series of alkenes with 2,3,4,5-tetrahydropyridine 1-oxide has been carried out.The high degree of both regiochemical and stereochemical control observed in these reactions has been explained in terms of maximum overlap of frontier orbitals, repulsive steric encumbrance, and attractive secondary orbital interaction in the transition state.Most monosubstituted and 1,1-disubstituted alkenes gave 2-substituted cycloadducts.As the electron affinity of the monosubstituted alkene increases, an increasing tendency towards formation of the regioisomeric 3-substituted cycloadduct is encountered. 1,2-Disubstituted alkenes undergo cycloadditions to afford cycloadducts with electron-withdrawing substituents always in the C-3 position of the cycloadducts.Significant secondary orbital interaction is observed with the non-conjugated hydroxymethyl substituent.
