N- to C-sulfonyl photoisomerisation of dihydropyridinones : a synthetic and mechanistic study
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The scope and limitations of a photoinitiated N- to C-sulfonyl migration process within a range of dihydropyridinones is assessed. This sulfonyl transfer proceeds without erosion of either diastereo- or enantiocontrol, and is general across a range of N-sulfonyl substituents (SO2R; R = Ph, 4-MeC6H4, 4-MeOC6H4, 4-NO2C6H4, Me, Et) as well as C(3)-(aryl, heteroaryl, alkyl and alkenyl) and C(4)-(aryl and ester) substitution. Crossover reactions indicate an intermolecular step is operative within the formal migration process, although no crossover from C-sulfonyl products was observed. EPR studies indicate the intermediacy of a sulfonyl radical and a mechanism is proposed based upon these observations.
Yeh , P-P , Taylor , J E , Stark , D G , Daniels , D S B , Fallan , C , Walton , J C & Smith , A D 2017 , ' N- to C-sulfonyl photoisomerisation of dihydropyridinones : a synthetic and mechanistic study ' Organic & Biomolecular Chemistry , vol 15 , no. 42 , pp. 8914-8922 . DOI: 10.1039/C7OB01699A
Organic & Biomolecular Chemistry
Copyright 2017 the authors. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence
DescriptionThe authors thank the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013) ERC Grant Agreement no. 279850 (CF and JET) and EPSRC grant number EP/J018139/1 (DSBD) for funding. ADS thanks the Royal Society for a Wolfson Research Merit Award.
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