- Asymmetric Catalytic Epoxidation of Terminal Enones for the Synthesis of Triazole Antifungal Agents
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An enantioselective epoxidation of α-substituted vinyl ketones was realized to construct the key epoxide intermediates for the synthesis of various triazole antifungal agents. The reaction proceeded efficiently in high yields with good enantioselectivities by employing a chiral N,N′-dioxide/ScIII complex as the chiral catalyst and 35% aq. H2O2 as the oxidant. It enabled the facile transformation for optically active isavuconazole, efinaconazole, and other potential antifungal agents.
- He, Qianwen,Zhang, Dong,Zhang, Fengcai,Liu, Xiaohua,Feng, Xiaoming
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p. 6961 - 6966
(2021/09/11)
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- Br?nsted Base-Catalyzed Transformation of α,β-Epoxyketones Utilizing [1,2]-Phospha-Brook Rearrangement for the Synthesis of Allylic Alcohols Having a Tetrasubstituted Alkene Moiety
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A stereoselective transformation of α,β-epoxyketones into alkenylphosphates having a hydroxymethyl group on the β-carbon was established by utilizing the [1,2]-phospha-Brook rearrangement under Br?nsted base catalysis. The reaction involves the catalytic generation of an α-oxygenated carbanion located at the α-position of an epoxide moiety through the [1,2]-phospha-Brook rearrangement and the following epoxide opening. Further transformation of the alkenylphosphates by the palladium-catalyzed cross-coupling reaction with Grignard reagents provided allylic alcohols having a stereodefined all-carbon tetrasubstituted alkene moiety.
- Kondoh, Azusa,Tasato, Naoko,Aoki, Takuma,Terada, Masahiro
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p. 5170 - 5175
(2020/07/04)
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- Ttimethylsilyl Cyanide - A Reagent for Umpolung, XVIII. - Nucleophilic Acylation of α-Chlorocarbonyl Compounds - a Novel and Diastereoselective Approach to Substituted α,β-Epoxy Ketones
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The addition products of trimethylsilyl cyanide and benzaldehyde (1a), furfural (1b), and α,β-unsaturated aldehydes 2a-c, respectively, react after deprotonation with α-chloroaldehydes and -ketones 3a-d.By 1,4-O,O-silyl rearrangement and cyanide elimination O-trimethylsilyl acyloins 4 and 9, respectively, are formed.With fluoride, 4 and 9 react to α,β-epoxy ketones 5 and 10 in high yield and with E/Z selectivities from 80:20 to >95:5.By this novel route even α,β-unsaturated epoxy ketones (10) become available.
- Huenig, Siegfried,Marschner, Claus
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p. 107 - 114
(2007/10/02)
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