Asymmetric Brønsted Acid Catalyzed Nucleophilic Addition to in situ Generated Chiral N-Acyliminium Ions
作者:Magnus Rueping、Boris Nachtsheim
DOI:10.1055/s-0029-1218539
日期:2010.1
A new enantioselective Bronsted acid catalyzed nucleophilic substitution of γ-hydroxylactams with indole is presented. The reaction proceeds via an intermediary N-acyliminium ion and provides disubstituted γ-lactams in good yields and with high enantioselectivities.
Triflic Anhydride Mediated Cyclization of 5-Hydroxy-Substituted Pyrrolidinones for the Preparation of α-Trifluoromethylsulfonamido Furans
作者:Albert Padwa、Paitoon Rashatasakhon、Mickea Rose
DOI:10.1021/jo0341970
日期:2003.6.1
(Tf(2)O) in pyridine resulted in the formation of various substituted sulfonamidofurans. The suggested mechanism involves initial formation of an iminium ion which is subsequently transformed into a transient imino triflate. Cyclization of the highly electrophilic imine onto the oxygen atom of the adjacent carbonyl group generates an imino dihydrofuran intermediate. This species reacts further with
The Reaction of Cyclic Carbinol Amides with Triflic Anhydride as a Method to Prepare α-Trifluoromethyl-Sulfonamido Furans
作者:Paitoon Rashatasakhon、Albert Padwa
DOI:10.1021/ol0272388
日期:2003.1.1
[reaction: see text] A novel synthesis of alpha-trifluoromethyl-sulfonamido furans via the reaction of cyclic carbinol amides with triflicanhydride has been developed. The reaction proceeds under very mild conditions with a wide set of representative lactams to provide the alpha-trifluoromethyl-sulfonamido-substituted furan in high yield. Rapid access to a 5-substituted indoline can be achieved by