436145-75-4Relevant academic research and scientific papers
Double asymmetric intramolecular aza-Michael reaction: a convenient strategy for the synthesis of quinolizidine alkaloids
Alzuet-Pi?a, Gloria,Escolano, Marcos,Sánchez-Roselló, María,Torres, Javier,del Pozo, Carlos
, p. 8740 - 8745 (2021/10/22)
A new methodology to access the quinolizidine skeleton in an asymmetric fashion was devised. It involves two consecutive intramolecular aza-Michael reactions of sulfinyl amines bearing a bis-enone moiety, in turn generated by a monodirectional cross metat
Biomimetic Organocatalytic Approach to 4-Arylquinolizidine Alkaloids and Application in the Synthesis of (-)-Lasubine II and (+)-Subcosine II
Virk, Seerat,Pansare, Sunil V.
supporting information, p. 5524 - 5528 (2019/07/08)
An enantioselective, biomimetic organocatalytic synthesis of 4-arylquinolizidin-2-ones, key intermediates in the synthesis of several Lythraceae alkaloids, was developed. The methodology features S-proline-mediated Mannich/aza-Michael reactions of readily available arylideneacetones and Δ1-piperideine. The total syntheses of (-)-lasubine II and (+)-subcosine II as well as the formal syntheses of structurally related Lythraceae alkaloids were achieved. The use of Δ1-pyrroline in the Mannich/aza-Michael reaction provides enantiomerically enriched 5-arylindolizidin-7-ones, which are precursors to nonopiate antinociceptive agents.
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.
Copper(I)-catalyzed enantioselective incorporation of ketones to cyclic hemiaminals for the synthesis of versatile alkaloid precursors
Shi, Shi-Liang,Wei, Xiao-Feng,Shimizu, Yohei,Kanai, Motomu
, p. 17019 - 17022,4 (2012/12/12)
A general catalytic enantioselective method that can produce five-, six-, and seven-membered N-heterocycles possessing various ketone moieties starting from stable and easily available cyclic hemiaminals and ketones was developed. The method involves three successive steps in one pot (aldol addition, dehydration, and enantioselective intramolecular aza-Michael reaction), all of which are promoted by a chiral copper(I)-conjugated Bronsted base catalyst. This method is useful for rapid access to versatile chiral building blocks for the synthesis of drug-lead alkaloids.
Copper(I)-catalyzed enantioselective incorporation of ketones to cyclic hemiaminals for the synthesis of versatile alkaloid precursors
Shi, Shi-Liang,Wei, Xiao-Feng,Shimizu, Yohei,Kanai, Motomu
, p. 17019 - 17022 (2013/01/15)
A general catalytic enantioselective method that can produce five-, six-, and seven-membered N-heterocycles possessing various ketone moieties starting from stable and easily available cyclic hemiaminals and ketones was developed. The method involves three successive steps in one pot (aldol addition, dehydration, and enantioselective intramolecular aza-Michael reaction), all of which are promoted by a chiral copper(I)-conjugated Bronsted base catalyst. This method is useful for rapid access to versatile chiral building blocks for the synthesis of drug-lead alkaloids.
Catalytic enantioselective approach to the stereodivergent synthesis of (+)-lasubines I and II
Mancheno, Olga Garcia,Arrayas, Ramon Gomez,Adrio, Javier,Carretero, Juan C.
, p. 10294 - 10297 (2008/03/28)
(Chemical Equation Presented) A concise and efficient approach to the stereodivergent synthesis of (+)-lasubines I and II is described. The key common intermediate is a chiral N-sulfonyl 2,3-dihydropyridone obtained by a novel Cu-catalyzed asymmetric form
Total Synthesis of (-)-lasubine II by the conjugate addition and intramolecular acylation of an amino ester with an acetylenic sulfone.
Back, Thomas G,Hamilton, Michael D
, p. 1779 - 1781 (2007/10/03)
[reaction: see text] The conjugate addition of methyl (S)-(2-piperidyl)acetate (3) to 2-(3,4-dimethoxyphenyl)-1-(p-toluenesulfonyl)ethyne (4), followed by LDA-promoted intramolecular acylation, stereoselective reduction, and desulfonylation, afforded (-)-
