Chemo-enzymatic total synthesis of 3-epiaustraline, australine, and 7-epialexine
Sequential enzymatic aldol reaction and bis-reductive amination leads to the total syntheses of tetrahydroxylated pyrrolizidine alkaloids, 3-epiaustaline (14), australine (1), and 7-epialexine (11). This approach allows for their rapid construction without the need for protecting group manipulation of the hydroxyl functionality. In addition, an improved procedure for the asymmetric epoxidation of divinyl carbinol (3) was described, and the product was used in a concise synthesis of the required triol 7 and ent-7.
1-EPIAUSTRALINE, A NEW PYRROLIZIDINE ALKALOID FROM CASTANOSPERMUM AUSTRALE
A new pyrrolizidine alkaloid has been isolated from the legume Castanospermum australe A.Cunn. (Leguminosae) and identified as (1S,2R,3R,7S,7aR)-3-hydroxymethyl-1,2,7-trihydroxypyrrolizidine on the basis of (1)H NMR nuclear Overhauser effects and other spectroscopic studies.
Total synthesis of uniflorine A, casuarine, australine, 3-epi-australine, and 3,7-di-epi-australine from a common precursor
(Chemical Equation Presented) Aflexible method for the diastereoselective total synthesis of the pyrrolizidine alkaloids uniflorine A, casuarine, australine, and 3-epi-australine and the unnatural epimer 3,7-di-epi-australine from a common chiral 2,5-dihydropyrrole precursor is described. 2009 American Chemical Society.
Ritthiwigrom, Thunwadee,Willis, Anthony C.,Pyne, Stephen G.
supporting information; experimental part
p. 815 - 824
(2010/06/15)
Enantioselective total syntheses of (+)-castanospermine, (+)-6- epicastanospermine, (+)-australine, and (+)-3-epiaustraline
The total syntheses of the potent glycosidase inhibitors castanospermine ((+)-1), 6-epicastanospermine ((+)-2), australine ((+)-3), and 3- epiaustraline ((+)-4) are described. The syntheses of indolizidine alkaloids (+)-1 and (+)-2 were accomplished in ei
Denmark, Scott E.,Martinborough, Esther A.
p. 3046 - 3056
(2007/10/03)
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