%0 Journal Article %A Bates, Roderick W. %A Lu, Yongna %D 2010 %T Synthesis of (−)-Sedinine by Allene Cyclization and Iminium Ion Chemistry %U https://acs.figshare.com/articles/journal_contribution/Synthesis_of_Sedinine_by_Allene_Cyclization_and_Iminium_Ion_Chemistry/2735929 %R 10.1021/ol1016492.s002 %2 https://ndownloader.figshare.com/files/4412668 %K Allene Cyclization %K semicyclic %K bicyclic %K cyclization %K iminium ions %K metathesi %K hydroxylamine %K allenic %K silyl enol ether %K consideration %K conformation %K Sedinine %K acetal %K synthesis %K opening %K conversion %K Lewis acidic conditions %K stereoselectivity %K Iminium Ion Chemistry %K tran %K sedum alkaloid sedinine %K Synthesi %X 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. %I ACS Publications