Synthesis of (-)-sedinine by allene cyclization and iminium ion chemistry.
A synthesis of the sedum alkaloid sedinine has been achieved employing silver(I)-catalyzed allenic hydroxylamine cyclization and ring-closing metathesis to form a bicyclic N,O-acetal. Ring opening of this acetal with a silyl enol ether under Lewis acidic conditions is exclusively trans selective, leading to the natural product after reduction. On the other hand, conversion of the bicyclic N,O-acetal to a semicyclic N,O-acetal results in no stereoselectivity during such a reaction. The contrasting results can be rationalized by consideration of the conformation of the iminium ions.
Bates
Roderick W
RW
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371. roderick@ntu.edu.sg
Lu
Yongna
Y
D000466:Alkadienes / Q000737:chemistry*; D000470:Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D058116:Lewis Acids / Q000737:chemistry; D015394:Molecular Structure; D031963:Sedum / Q000737:chemistry; D013237:Stereoisomerism
D000466:Alkadienes; D000470:Alkaloids; D058116:Lewis Acids; C553777:sedinine; C025947:propadiene