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Synfacts 2017; 13(03): 0265
DOI: 10.1055/s-0036-1589975
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Ruthenium-Catalyzed Asymmetric Photocycloaddition of 2′-Hydroxychalcones

Contributor(s):
Hisashi Yamamoto
,
Wataru Muramatsu
Blum TR. Miller ZD. Bates DM. Guzei IA. Yoon TP. * University of Wisconsin-Madison, USA
Enantioselective Photochemistry through Lewis Acid-Catalyzed Triplet Energy Transfer.

Science 2017;
354: 1391-1395
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Further Information

Publication History

Publication Date:
15 February 2017 (online)

 
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Key words

ruthenium catalysis - photocatalysis - photocycloaddition - hydroxychalcones - dienes

Significance

A chiral scandium–ligand complex was shown to catalyze triplet energy transfer from an electronically excited photosensitizer. This strategy can be applied to the asymmetric [2+2] photocycloaddition of 2′-hydroxychalcones and dienes with tris(bipyridyl)ruthenium(II) as a sensitizer.


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Comment

This protocol permits ready access to chiral [2+2] cycloadducts bearing three contiguous stereocenters in good yields and with high enantioselectivities. Several lines of evidence support a mechanism in which the coordination of the scandium catalyst dramatically lowers the triplet energy of the 2′-hydroxychalcone.


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