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Direct and Stereoselective Synthesis of Diversely Substituted 2,4‐ trans ‐(NH)‐Pyrrolidines by Copper(I)‐Catalyzed Radical Cyclization at Low Temperature
Author(s) -
Ram Ram N.,
Gupta Dharmendra Kumar
Publication year - 2016
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201600844
Subject(s) - chemistry , stereoselectivity , catalysis , copper , sulfoxide , amine gas treating , combinatorial chemistry , pyrrole , dimethyl sulfoxide , medicinal chemistry , trichloroacetic acid , organic chemistry
This work describes a successful copper(I)‐catalyzed radical cyclization of β‐haloethylallylamines bearing an unprotected NH‐group while retaining catalyst‐redox activity. The cyclization occurs regio‐ and diastereoselectively at 0 °C and furnishes diversely substituted 1,3‐ trans ‐(NH)‐pyrrolidines directly in high isolated yields. An involvement of the bulky copper complex in the cyclization step as the possible reason for the diastereoselectivity was proposed. Synthetic applications of the products in the preparation of useful 4‐chloro‐NH‐pyrrole in a single step, has also been demonstrated. A quick, mild and general method involving simple addition of trichloroacetic acid/dimethyl sulfoxide (CCl 3 CO 2 H‐DMSO) solution to readily accessible N ‐allylaldimines and ketimines tolerating acid‐sensitive and highly deactivating substituents was developed to access the amine precursors.