Quadrone structural and synthetic studies. Total synthesis of natural (-)-quadrone, the (+)-enantiomer, and the racemate. Conformational analysis, circular dichroism, and determination of absolute stereochemistry.

1991 ◽  
Vol 113 (9) ◽  
pp. 3533-3542 ◽  
Author(s):  
Amos B. Smith ◽  
Joseph P. Konopelski ◽  
Barry A. Wexler ◽  
Paul A. Sprengeler
Keyword(s):  
Circular Dichroism ◽  
Total Synthesis ◽  
Conformational Analysis ◽  
Synthetic Studies ◽  
Circular Dichroïsm ◽  
Absolute Stereochemistry

(-)-Strempeliopine, stereoselective total synthesis and the determination of absolute configuration

1986 ◽  
Vol 51 (8) ◽  
pp. 1731-1742 ◽  
Author(s):  
Josef Hájíček ◽  
Jan Trojánek
Keyword(s):  
Circular Dichroism ◽  
Total Synthesis ◽  
Absolute Configuration ◽  
Determination Of Absolute Configuration ◽  
Natural Base ◽  
The Absolute ◽  
Circular Dichroïsm

A synthesis of (±)-strempeliopine (II) is described, the key step of which is the stereoselective reductive rearrangement of 18-methylene-1,2-dehydroaspidospermidine (XI). The absolute configuration of the natural (-)-base II was determined as (2S, 7R, 20R, 21R) on the basis of its synthesis from (+)-18-methylenevincadifformine (XVII) the configuration of which was derived from a comparison of circular dichroism properties of bases with a β-anilinoacrylate chromophore. The biogenesis of the alkaloids of the schizozygane type is discussed.

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