- Tunable cyclization strategy for the synthesis of zizaene-, allo- cedrane-, seco-kaurane-, and seco-atesane-type skeletons
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A versatile Lewis acid-mediated cyclization strategy has been developed for selectively establishing zizaene-, allo-cedrane-, seco-kaurane-, and secoatesane- type skeletons. The zizaene- and seco-atesane-type skeletons can be obtained in a cascade manner, which involves Diels-Alder reaction of cyclic enones with bissilyloxy dienes and carbocyclization of yne-enolates through Lewis acid dependent 5- or 6-exo-dig modes. This cyclization strategy was also employed for the core synthesis of tashironin.
- Yang, Qianqian,Ma, Wenjing,Wang, Gaopeng,Bao, Wenli,Dong, Xiaoshu,Liang, Xuefeng,Zhu, Lizhi,Lee, Chi-Sing
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- Different synthetic routes towards efficient organogelators: 2,3-substituted anthracenes
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Three synthetic approaches towards 2,3-substituted anthracenes are reported and discussed in terms of selectivity and viability. This allowed us to introduce a variety of substituents as sidearms. Promising results have been found using a tandem Diels-Alder aromatization reaction using 2,2,3-dimethoxybuladiene 9 as a key intermediate. However, for multigram preparations the Friedel-Crafts approach is preferred.
- Pozzo, Jean-Luc,Clavier, Gilles M.,Colomes, Michel,Bouas-Laurent, Henri
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p. 6377 - 6390
(2007/10/03)
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- Reactions of Trialkylsilyl Trifluoromethanesulfonates, I. - Synthesis of Trialkylsilyl Enol Ethers
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The reactions of the ketones 2,2-bromoketones 6, α,β-unsaturated ketones 8, 1,2-diketones, and aliphatic aldehydes 20 with trialkylsilyl triflates 1 in the presence of triethylamine (4) at room temperature yield the silyl enol ethers 3, 7, 9, 11, and 21.The silylation of the unsymmetrical ketones 12 with 1a/4 runs regioselectively in the thermodynamical sense using 1a/12 in excess and yields the enol ethers 13t.The course of this reaction is discussed briefly.
- Emde, Herbert,Goetz, Andreas,Hofmann, Karin,Simchen, Gerhard
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p. 1643 - 1657
(2007/10/02)
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