- Light-Driven Vitamin B12-Catalysed Generation of Acyl Radicals from 2-S-Pyridyl Thioesters
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Acyl radicals are invaluable intermediates in organic synthesis, however their generation remains challenging. Herein, we present an unprecedented light-driven, cobalt-catalysed method for the generation of acyl radicals from readily available 2-S-pyridyl thioesters. The synthetic potential of this methodology was demonstrated in the Giese-type acylation of activated olefins in the presence of heptamethyl cobyrrinate. This vitamin B12 derivative proved to be the most efficient catalyst in the studied process. The developed method features broad substrate scope (38 examples), good functional group tolerance, and mild reaction conditions. Moreover, it is easily scalable (illustrated on a 20-fold scale-up procedure), enabling its preparative use. Mechanistic studies revealed that the reaction proceeds via a radical pathway with the key steps involving the formation of an acyl-vitamin B12 complex and subsequent photolysis of the Co?C bond. (Figure presented.).
- Ociepa, Micha?,Baka, Oskar,Narodowiec, Jakub,Gryko, Dorota
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supporting information
p. 3560 - 3565
(2017/10/24)
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- Diastereoselective Aldol Condensation of Silyl Ketene Acetal of 2-Pyridyl Thioester with Benzaldehyde
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The TiCl4-mediated aldol reaction of the (E)-O-silyl ketene-O,S-acetal derived from 2-pyridyl thioester with benzaldehyde gave exclusively syn-aldol product.In contrast, BF3-mediated reaction afforded the corresponding anti-isomer as a major product.Chela
- Suh, Kwee-Hyun,Choo, Dong-Joon
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p. 6109 - 6112
(2007/10/02)
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- MILD AND CONVENIENT ONE-POT SYNTHESIS OF β-LACTAMS BY CONDENSATION OF TITANIUM ENOLATES OF 2-PYRIDYLTHIOESTERS WITH IMINES
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Treatment of 2-pyridylthioesters with triethylamine in the presence of titanium tetrachloride affords titanium enolates that add to imines to give β-lactams in fair to excellent yields with moderate to good stereoselectivity.
- Cinquini, Mauro,Cozzi, Franco,Cozzi, Pier Giorgio,Consolandi, Emanuela
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p. 8767 - 8774
(2007/10/02)
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