Document Detail

Brønsted acid cocatalysts in photocatalytic radical addition of α-amino C-H bonds across Michael acceptors.
MedLine Citation:
PMID:  23537318     Owner:  NLM     Status:  MEDLINE    
In marked contrast to the variety of strategies available for oxidation and nucleophilic functionalization of methylene groups adjacent to amines, relatively few approaches for modification of this position with electrophilic reaction partners have been reported. In the course of an investigation of the reactions of photogenerated α-amino radicals with electrophiles, we made the surprising observation that the efficiency of radical photoredox functionalization of N-aryl tetrahydroisoquinolines is dramatically increased in the presence of a Brønsted acid cocatalyst. Optimized conditions provide high yields and efficient conversion to radical addition products for a range of structurally modified tetrahydroisoquinolines and enones using convenient household light sources and commercially available Ru(bpy)3Cl2 as a photocatalyst. Our investigations into the origins of this unexpected additive effect have demonstrated that the carbon-carbon bond-forming step is accelerated by TFA and is a rare example of Brønsted acid catalysis in radical addition reactions. Moreover, a significant conclusion arising from these studies is the finding that product formation is dominated by radical chain processes and not by photocatalyst turnover. Together, these findings have important implications for the future design and mechanistic evaluation of photocatalytic radical processses.
Laura Ruiz Espelt; Eric M Wiensch; Tehshik P Yoon
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2013-04-10
Journal Detail:
Title:  The Journal of organic chemistry     Volume:  78     ISSN:  1520-6904     ISO Abbreviation:  J. Org. Chem.     Publication Date:  2013 Apr 
Date Detail:
Created Date:  2013-04-19     Completed Date:  2013-08-12     Revised Date:  2014-04-22    
Medline Journal Info:
Nlm Unique ID:  2985193R     Medline TA:  J Org Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4107-14     Citation Subset:  IM    
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MeSH Terms
Carbon / chemistry*
Hydrogen Bonding
Molecular Structure
Organometallic Compounds / chemistry*
Photochemical Processes
Ruthenium / chemistry*
Tetrahydroisoquinolines / chemistry*
Grant Support
Reg. No./Substance:
0/Organometallic Compounds; 0/Tetrahydroisoquinolines; 7440-44-0/Carbon; 7UI0TKC3U5/Ruthenium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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