Synthesis of (−)-Sedinine by Allene Cyclization and Iminium Ion Chemistry
Roderick W. Bates
Yongna Lu
10.1021/ol1016492.s001
https://acs.figshare.com/articles/journal_contribution/Synthesis_of_Sedinine_by_Allene_Cyclization_and_Iminium_Ion_Chemistry/2735935
A synthesis of the <i>sedum</i> alkaloid sedinine has been achieved employing silver(I)-catalyzed allenic hydroxylamine cyclization and ring-closing metathesis to form a bicyclic <i>N</i>,<i>O</i>-acetal. Ring opening of this acetal with a silyl enol ether under Lewis acidic conditions is exclusively <i>trans</i> selective, leading to the natural product after reduction. On the other hand, conversion of the bicyclic <i>N</i>,<i>O</i>-acetal to a semicyclic <i>N</i>,<i>O</i>-acetal results in no stereoselectivity during such a reaction. The contrasting results can be rationalized by consideration of the conformation of the iminium ions.
2010-09-03 00:00:00
Allene Cyclization
semicyclic
bicyclic
cyclization
iminium ions
metathesi
hydroxylamine
allenic
silyl enol ether
consideration
conformation
Sedinine
acetal
synthesis
opening
conversion
Lewis acidic conditions
stereoselectivity
Iminium Ion Chemistry
tran
sedum alkaloid sedinine
Synthesi