154874-92-7Relevant academic research and scientific papers
Intramolecular cyclizations of α-lithioamine synthetic equivalents: Convenient syntheses of 3-, 5-, and 6-membered-ring heterocyclic nitrogen compounds and elaborations of 3-membered ring systems
Beak,Wu,Eul Kyun Yum,Young Moo Jun
, p. 276 - 277 (1994)
A lithiation-intramolecular cyclization reaction of N-Boc chloroalkyl secondary amines is reported to provide the 2-aryl-substituted pyrrolidine and piperidines 6, 7, 9, and 11 and a series of 2-azabicyclo[3.1.0] derivatives 14-25, including cyclopropane derivatives of proline and of the indolizidine-pyrrolizidine alkaloid ring system. Lithiation-substitutions of N-Boc-N-ethylcyclopropylamine to give 27-29 and lithiation-silylations of N- Boc aziridines to give 31-33 also are reported.
Asymmetric syntheses of N-Boc 2-substituted pyrrolidines and piperidines by intramolecular cyclization
Serino,Stehle,Yong Sun Park,Florio,Beak
, p. 1160 - 1165 (2007/10/03)
Asymmetric lithiation-substitutions by n-BuLi/(-)-sparteine with the N- Boc-N-(3-halopropyl)allylamines 1-4 provide the N-Boc-2-alkenylpyrrolidines (S)-5, (S)-6, and (S)-7 in yields of 3193% with enantiomeric ratios (ers) from 65:35 to 90:10. These reactions are shown to involve an initial asymmetric deprotonation, but the enantiodetermining step is a subsequent asymmetric cyclization under the influence of the chiral ligand. Extension to formation of a piperidine is illustrated by reaction of N-Boc-(4- chlorobutyl)cinnamylamine (9) to afford (S)-N-Boc-2-(trans-β- styryl)piperidine ((S)-10) in 68% yield with an enantiomeric ratio (er) of 84:16. Analogous reactions with epoxide ring openings of N-Boc-N- (oxaalkenyl)benzylamines 11 and 12 afford the corresponding N-Boc-2-phenyl- 3-(hydroxymethyl)pyrrolidine (13) in 67% yield with a diastereomeric ratio (dr) of 50:50 and ers of 97:3 and 95:5 and the corresponding N-Boc-2-phenyl- 3-(hydroxymethyl)piperidine (14) in 29% yield with a dr of 86:14 and ers of 81:19 and 86:14.
