Lewis Acid-Mediated Rearrangement of Activated Cyclic Amines:  A Facile Synthetic Protocol for the Preparation of Amino Carbonyl Compounds

Abstract

Ring opening of activated cyclic amines to produce amino carbonyl compounds has been studied in the presence of Lewis acids. Whereas five- and six-membered rings cleave and rearrange via a 1,2-hydride shift, reaction in three- and four-membered rings takes place via a C-C bond migration. In the case of a three-membered ring, a wide variety of Lewis acids proved to be effective for the reaction. Base-induced ring opening of activated alpha,alpha-disubstituted azetidinemethanol and its mechanistic aspects have been studied.

Acid-Mediated C–N Bond Cleavage in 1-Sulfonylpyrrolidines: An Efficient Route towards Dibenzoxanthenes, Diarylmethanes, and Resorcinarenes

“…The structure of calixarene 6d was proved by 1D/2D NMR correlation experiments ( 1 H-1 H COSY, 1 H- 13 C HSQC, 1 H- 13 C HMBC 35,36 ). To further establish the conformation of calixarene 6d, additional 1D ROESY 37 experiments were carried out.…”

“…However, it is undoubtedly of interest since it allows the synthesis of bifunctional sulfamide derivatives in a one-step and one-pot manner with good to high yields. [7][8][9][10][11][12][13][14][15] Moreover, most of these reactions are stereoselective, which makes them important for the asymmetric synthesis. 8,9,[16][17][18] Reagents and approaches used for the C-N bond cleavage in N-sulfonylpyrrolidines vary widely.…”

“…For example, sodium in naphthalene, 19 sodium borohydride, 11 lithium alu-minohydride, 9 and hydrogen with a palladium catalyst 14 were used for the reductive N-sulfonylpyrrolidine ring opening. Usage of Grignard reagents 20,21 and Lewis acids 12,13 are also described. Other examples include iron-mediated С-N bond cleavage in N-nosylprolines, 22 silver oxide catalyzed Arndt-Eistert reaction of N-tosylproline, 23 synthesis of the aminoalcohols via Baeyer-Villiger oxidation of N-tosylpyrrolidine, and treatment of intermediate products with LiAlH 4 .…”