- 109. Reactivite de composes carbonyles avec des cetenes en presence d'alkoxydes de titane ou de zirconium
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Reactivity of Carbonyl Compounds with Ketenes in the Presence of Titanium or Zirconium Alkoxides.The reaction of ketene or dimethylketene with aldehydes or ketones in the presence of titanium or zirconium alkoxides gives essentially β-hydroxyesters.By polyinsertion of ketene and aldehydes in the Ti-O bond, di-, tri-, and tetraesters are formed.An excess of ketene produces acetyl derivatives of esters and 6-alkyl-3,4,5,6-tetrahydro-2,4-pyrandiones.
- Hofer, Roger,Evard, Daniel,Jacot-Guillarmod, Andre
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- TWO LACTONE FORMATION REACTIONS FROM 1,3-DIOXIN-4-ONES HAVING HYDROXYALKYL GROUP AT THE 6-POSITION: DIFFERENCE IN RING OPENING AND CLOSURE
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Two methods (A: ring opening to acylketenes followed by intramolecular ketene trapping and B: methoxide-mediated ring opening followed by cyclization of the hydroxy esters thus formed) have become available for the synthesis of lactones and/or cyclic ethers from 1,3-dioxin-4-ones having 1- 4-hydroxyalkyl group at the 6-position.Mechanism and scope of both methods have been clarified.
- Sato, Masayuki,Sakaki, Jun-ichi,Sugita, Yoshiaki,Yasuda, Sanae,Sakoda, Hiroko,Kaneko, Chikara
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p. 5689 - 5708
(2007/10/02)
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