%0 Generic
%A Dake, Gregory R.
%A Fenster, Michaël D. B.
%A Hurley, Paul B.
%A Patrick, Brian O.
%D 2004
%T Synthesis of Functionalized 1-Azaspirocyclic Cyclopentanones
Using Bronsted Acid or N-Bromosuccinimide Promoted Ring
Expansions
%U https://acs.figshare.com/articles/dataset/Synthesis_of_Functionalized_1_Azaspirocyclic_Cyclopentanones_Using_Bronsted_Acid_or_i_N_i_Bromosuccinimide_Promoted_Ring_Expansions/3327904
%R 10.1021/jo0493572.s004
%2 https://ndownloader.figshare.com/files/5167114
%K bromosuccinimide
%K semipinacol ring expansion reactions
%K electrophilic bromine source
%K Bromosuccinimide Promoted Ring Expansions Azaspirocyclic ring systems
%K Bronsted acid
%K Functionalized
%X Azaspirocyclic ring systems are present in a variety of alkaloids. Functionalized 1-azaspirocyclopentanones (6, 7, 11, 12) can be efficiently constructed through semipinacol ring expansion reactions
of 2-(1-hydroxycyclobutyl)-p-toluenesulfonylenamides (4) promoted by either a Bronsted acid ((S)-(+)-10-camphorsulfonic acid or HCl) or N-bromosuccinimide, an electrophilic bromine source.
Reactions promoted by N-bromosuccinimide tend to proceed in higher yields (80−95%) and with
greater diastereoselectivity (3:1−1:0) compared to those reactions promoted by a Bronsted acid. In
addition, N-bromosuccinimide promoted reactions can produce a complementary stereochemical
outcome compared to the reactions using Bronsted acid.
%I ACS Publications