251995-67-2Relevant academic research and scientific papers
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.
Protecting-Group-Directed Regio- and Stereoselective Oxymercuration-Demercuration: Synthesis of Piperidine Alkaloids Containing 1,2- and 1,3-Amino Alcohol Units
Bugde, Sandesh T.,Volvoikar, Prajesh S.,Tilve, Santosh G.
, p. 1113 - 1122 (2017/12/06)
An efficient synthesis of naturally occurring 1,2- and 1,3-amino alcohol unit containing 2-substituted piperidine alkaloids and their analogues has been developed from l -pipecolinic acid. The protocol describes the regio- and stereoselective oxymercuration-demercuration of 2-alkenyl piperidines based on protecting groups to give piperidine alkaloids as a key step.
Synthetic studies of alkaloids containing pyrrolidine and piperidine structural motifs
Bhat, Chinmay
, p. 192 - 196 (2015/04/27)
Avenues to asymmetric alkaloids! Various 2-substituted pyrrolidine and piperidine chiral bioactive natural products were synthesized using a 'chiral pool' method. l-proline and l-pipecolinic acids with one chiral center served as the best precursors for the synthesis of these alkaloids. Overall, 14 total synthetic and 11 formal synthetic approaches were developed.
Henry-Nef reaction: A practical and versatile chiral pool route to 2-substituted pyrrolidine and piperidine alkaloids
Bhat, Chinmay,Tilve, Santosh G.
, p. 6129 - 6143 (2013/07/27)
The paper describes the synergistic protocol developed by combinatorial Henry and Nef reaction for the synthesis of 2-substituted pyrrolidine and piperidine alkaloids containing 1,3-aminoketone and 1,3-amino alcohol units. The utility of the protocol is demonstrated by asymmetric synthesis of 12 natural products of which asymmetric synthesis of (-)-N-methylpelletierine is presented for the first time. The one-carbon homologation described also provides an alternate route for the synthesis of key intermediates homoprolinol and homopipecolinol used as synthetic precursors for several alkaloids and construction of β-amino acids from α-amino acids.
An efficient approach to 2-substituted N-tosylpiperdines: asymmetric synthesis of 2-(2-hydroxy substituted)piperidine alkaloids
Bisai, Alakesh,Singh, Vinod K.
, p. 1907 - 1910 (2007/10/03)
We have developed an efficient and a general approach to chiral 2-substituted N-tosylpiperidines starting from chiral α-substituted-N-tosylaziridines. Using this approach, we have synthesized (+)-coniine. The synthesis of chiral N-tosyl-2-piperidinylethanol 15 and ent-15, was achieved from l- and d-aspartic acids, respectively in few steps. Piperidine 15 was converted into 2-(2-hydroxysubstituted)piperidines of type 2 in optically active form. By applying this strategy, asymmetric syntheses of halosaline (R,R)-2a, (+)- and (-)-sedamine 2b, (+)- and (-)-allosedamine 2c, (+)- and (-)-sedridine 2d, (+)- and (-)-allosedridine 2e, (+)-tetraponerine T-3 3a, T-4 3c, T-7 3b, and T-8 3d have been achieved in high yields. These stereoisomers can be interconverted via Mitsunobu inversion in excellent yields.
A new synthesis of all four stereoisomers of 2-(2,3- dihydroxypropyl)piperidine via iterative asymmetric dihydroxylation to cause enantiomeric enhancement. Application to asymmetric synthesis of naturally occurring piperidine-related alkaloids
Takahata, Hiroki,Kubota, Minoru,Ikota, Nobuo
, p. 8594 - 8601 (2007/10/03)
Both enantiomers of 2-(2-propenyl)piperidine 1 (76-88% ee), prepared via the first asymmetric dihydroxylation (AD) of 5-hexenyl azide, underwent the second AD to provide all four of the stereoisomeric 2-(2,3- dihydroxypropyl)piperidines 2 with enantiomeric enhancement.(>98% ee). An asymmetric synthesis, starting from 2, of several 2-(2- hydroxyalkyl)piperidine alkaloids [(-)halosaline, (+)-N-methylallosedridine, (+)-8-ethylnorlobelol, (+)-sedridine, (+)-allosedridine, (-)allosedridine, and (+)-N-methylsedridine] and the ant defense alkaloids [(+)-tetraponerine-3 (T-3), T-4, T-7, and T-8] is demonstrated.
