142841-50-7Relevant academic research and scientific papers
General Entry to the 3,5-Disubstituted Indolizidine Class of Dendrobatid Alkaloids. Total Syntheses of Both Enantiomers of Indolizidines 195B, 223AB, 239AB, and 239CD from a Common Chiral Synthon
Machinaga, Nobuo,Kibayashi, Chihiro
, p. 5178 - 5189 (2007/10/02)
A general protocol for the total syntheses of both enantiomers of dendrobatid alkaloids, indolizidines 195B, 223AB, 239AB, and 239CD, belonging to the 3,5-disubstituted indolizidine subclass is described, in which 3,4-dideoxy-D-threo-hexitol (8) has been used as single and common chiral synthon.The syntheses of the (+)- and (-)-enantiomers of these alkaloids begin with (S,S)- and (R,R)-1,2:5,6-diepoxyhexanes (7), respectively, both of which were derived from 8 in three steps and are carried out by way of pyrrolidine formation via the cyclic sulfates leading to the(2R,5R)- and (2S,5S)-trans-2,5-dialkylated pyrrolidines, which were converted to the (+)- and (-)-enantiomers, respectively, of the title indolizidine alkaloids.These syntheses involve the first chiral preparations of indolizidines 239AB, 239CD both in natural (-)- and unnatural (+)-enantiomeric forms, which confirm the absolute configurations of natural 239AB and 239CD as 3R,5S,8aR and 3R,5R,8aR, respectively.
Improved syntheses of both enantiomers of 1,2,5,6-diepoxyhexane from (2S,5S)-1,2,5,6-hexanetetrol
Machinaga,Kibayashi
, p. 989 - 994 (2007/10/02)
Several methods for the preparation of (2R,5R)- and (2S,5S)-1,2,5,6-diepoxyhexane (2) from 3,4-dideoxy-D-threo-hexitol [(2S,5S)-1,2,5,6-hexanetetrol (1)] as a single common chiral synthon are described. Among these methods, the methods via (2S,5S)-1,6-bis(pivaloyloxy)-2,5-hexanediol and (2S,5S)-2,5-bis(benzoyloxy)-1,6-dibromohexane, both derived from 1, provide the best results in terms of the selectivity, yield, and optical purity for the preparation of (R,R)-2 and (S,S)-2, respectively.
