- An Enolate-Structure-Enabled Anionic Cascade Cyclization Reaction: Easy Access to Complex Scaffolds with Contiguous Six-, Five-, and Four-Membered Rings
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Catalyst-free addition of ketone enolate to non-activated multiple C?C bonds involves non-complementary reaction partners and typically requires super-basic conditions. On the other hand, highly aggregated or solvated enolates are not reactive enough to undergo direct addition to alkenes or alkynes. Herein, we report a new anionic cascade reaction for one-step assembly of intriguing molecular scaffolds possessing contiguous six-, five-, and four-membered rings, representing a formal [2+2] enol–allene cycloaddition. Reaction proceeds under very mild conditions and with excellent diastereoselectivity. Deeper mechanistic and computational studies revealed unusually slow proton transfer phenomenon in cyclic ketone intermediate and explained peculiar stereochemical outcome.
- Buk?naitien?, Rita,Javorskis, Tomas,Jurys, Arminas,Karpavi?ien?, Ieva,Orentas, Edvinas,Snarskis, Gustautas
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supporting information
p. 20120 - 20128
(2020/09/02)
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- Benzofuran Derivatives. Part 4. Synthesis of Benzofurans and 2,3,4,5-Tetrahydro-1-benzoxepin-3,5-diones
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By treatment of ethyl 4- or 5-substituted 2-acetylphenoxyacetates 1 with potassium hydroxide in dry dioxane, benzofurans 2-7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 were obtained.The relative yields of benzofurans 2-7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 varied with the types of 4- or 5-substituents.The electron-donating 4-methoxyl group favored the formation of benzoxepins.On the other hand, electron-withdrawing substituents such as the 4-nitro group favored the formation of benzofurans.When esters 1 were treated with sodium amide,2,3-dihydrobenzofurans 2 were obtained exclusively regardless of 4- or 5-substituents.
- Suzuki, Tsuneo,Tanemura, Kiyoshi,Horaguchi, Takaaki,Shimimizu, Takahachi,Sakakibara, Tohru
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p. 423 - 429
(2007/10/02)
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- Synthesis of 3-amino-2,3,4,5-tetrahydro-1-benzoxepine-5-ols and their action on gastric motility
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3-Amino-2,3,4,5-tetrahydro-1-benzoxepine-5-ols are synthesized by condensation of 2,3,4,5-tetrahydro-1-benzoxepine-3,5-diones with amines and subsequent one or two step reduction. The pharmacological action of these compounds on the gastric motility of anesthetized rats is described. The effects both after parenteral and after enteral application were determined using a pressure recording technique. Dose response curves of KC 2450 (rac. cis-3-methylamino-2,3,4,5-tetrahydro-1-benzoxepine-5-ol hydrochloride; prop. INN for the base: exepanol) and of domperidone are given.
- Kaupman,Ohlendorf,Wolf
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p. 207 - 212
(2007/10/02)
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