Organophotocatalysis: Insights into the Mechanistic Aspects of Thiourea-Mediated Intermolecular [2+2] Photocycloadditions

Nandini Vallavoju; Sermadurai Selvakumar; Barry C Pemberton; Steffen Jockusch; Mukund P Sibi; Jayaraman Sivaguru

doi:10.1002/anie.201600596

Organophotocatalysis: Insights into the Mechanistic Aspects of Thiourea-Mediated Intermolecular [2+2] Photocycloadditions

Angew Chem Int Ed Engl. 2016 Apr 25;55(18):5446-51. doi: 10.1002/anie.201600596. Epub 2016 Mar 23.

Authors

Nandini Vallavoju¹, Sermadurai Selvakumar¹, Barry C Pemberton¹, Steffen Jockusch², Mukund P Sibi³, Jayaraman Sivaguru⁴

Affiliations

¹ Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND, 58108-6050, USA.
² Department of Chemistry, Columbia University, New York, NY, 10025, USA.
³ Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND, 58108-6050, USA. mukund.sibi@ndsu.edu.
⁴ Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND, 58108-6050, USA. jayaraman.sivaguru@ndsu.edu.

PMID: 27005562
DOI: 10.1002/anie.201600596

Abstract

Mechanistic investigations of the intermolecular [2+2] photocycloaddition of coumarin with tetramethylethylene mediated by thiourea catalysts reveal that the reaction is enabled by a combination of minimized aggregation, enhanced intersystem crossing, and altered excited-state lifetime(s). These results clarify how the excited-state reactivity can be manipulated through catalyst-substrate interactions and reveal a third mechanistic pathway for thiourea-mediated organo-photocatalysis.

Keywords: asymmetric catalysis; organocatalysis; photochemistry; photocycloadditions; thioureas.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Alkenes / chemistry*
Catalysis
Coumarins / chemistry*
Cycloaddition Reaction
Light
Models, Molecular
Photochemical Processes
Thiourea / chemistry*

Substances

Alkenes
Coumarins
2,3-dimethyl-2-butene
coumarin
Thiourea