154472-03-4Relevant academic research and scientific papers
Stereoselective multicomponent assembly of enantiopure oxazolopiperidines and -azepines
Zill, Nicolas,Schoenfelder, Angele,Girard, Nicolas,Taddei, Maurizio,Mann, Andre
, p. 2246 - 2253 (2012/05/20)
A multicomponent reaction (MCR) based on a cyclohydrocarbonylation (CHC) driven by hydroformylation was set up toward the efficient diastereoselective preparation of oxazolopiperidines (4a-e) and -azepines (7a-d). The bicyclic oxazolidines were obtained from chiral N-alkenylamino alcohols via transient cyclic iminium intermediates that underwent an intramolecular cyclization from the appendant oxygen. On the basis of a series of different experimental conditions, the diastereocontrol observed during the formation of the oxazolidines is best explained by the stereoelectronic effect induced by an A1,3-strain in a common cyclic iminium intermediate (A). This new sequence is suitable for diversity oriented syntheses, allowing the preparation of enantiopure (S)- and (R)-coniceine in five steps from commercially available material.
Preparation of (R)-(+)-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridin-4-ylium bromide: synthesis of (S)-(+)-coniine, (R)-(-)-coniceine and (R)-(+)-anabasine
Castro, Alejandro,Ramirez, Johana,Juarez, Jorge,Teran, Joel L.,Orea, Laura,Galindo, Alberto,Gnecco, Dino
, p. 2699 - 2708 (2008/09/19)
We describe the transformation of (R)-(-)-1-(2'-hydroxy-1'-phenylethyl)piperidin-2-one 1 into (R)-(-)-3-phenyl-2,3,5,6,7,8-hexahydro-oxazolo[3,2-a]pyridin-4-ylium bromide 2 using POBr3. Reduction of 2 with Red-Al at -78 °C gave (3R,8aR)-(-)-3-phenylhexahydro-2H-oxazolo[3,8-a]-pyridine 3 as a single diastereoisomer. The synthetic potential of these transformation is illustrated by the enantiopure synthesis of (S)-(+)-coniine, (R)-(-)-coniceine and (R)-(+)-anabasine.
New piperidine scaffolds via nucleophilic reactivity of (-)-phenyloxazolopiperidine
Poupon, Erwan,Francois, David,Kunesch, Nicole,Husson, Henri-Philippe
, p. 3836 - 3841 (2007/10/03)
The present work illustrates the power of compound 2 as a chiral, nonracemic, and stable 2-piperideine (enamine) equivalent in the rapid and efficient construction of 3-substituted piperidines (carbon-carbon and carbon-sulfur bonds) such as 3-spiropiperidines. This methodology offers a new route to such systems that could compete with previously reported strategies.
Reductive and oxidative transformations of the N-(cyanomethyl)oxazolidine system to expand the chiral pool of piperidines
Francois, David,Poupon, Erwan,Kunesch, Nicole,Husson, Henri-Philippe
, p. 4823 - 4829 (2007/10/03)
Two new reactions have been exploited to modify piperidine scaffolds containing the chiral, non-racemic N-(cyanomethyl)oxazolidine system. A Raney nickel mediated decyanation was studied first, followed by an oxidative process using potassium permanganate
An expeditious total synthesis of the natural stereomeric mixture of stenusine following a possible biogenetic pathway
Poupon, Erwan,Kunesch, Nicole,Husson, Henri-Philippe
, p. 1493 - 1495 (2007/10/03)
New insight into the biogenetic origin of stenusine 1, the spreading agent of the beetle Stenus comma, is gained from the results of a one-pot synthesis of the natural and the racemic compound. On the basis of these results a plausible biogenetic pathway
1,4-Dihydropyridines from Dithionite Reduction of Pyridinium Salts without Electron-Withdrawing Groups as Substituents
Wong, Yung-Sing,Marazano, Christian,Gnecco, Dino,Das, Bhupesh C.
, p. 707 - 710 (2007/10/02)
Conditions have been established for the sodium dithionite (Na2S2O4) reduction of pyridinium salts 1 lacking electron-withdrawing substituents to their corresponding 1,4-dihydropyridines (1,4-DHPs) 2, a reaction which was previously reported to fail.The i
