- Exaltone (=Cyclopentadecanone) from Isomuscone (=Cyclohexadecanone), a one-C-atom ring-contraction methodology via a stereospecific favorskii rearrangement: Regioselective application to (-)-(R)-muscone
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Treatment of cyclohexadecanone (1g; with I2 (2.2 mol-euqiv.) and KOH in MeOH) furnished the unsaturated (Z)-ester 2g in 83% yield, via a stereospecific Favorskii rearrangement (Scheme 1). Further treatment with 3-chloroperbenzoic acid (m-CPBA) afforded the unreported epoxy ester 3g (88% yield), which was cleaved in 33% yield to Exaltone (=cyclopentadecanone; 1f) with NaOH in MeOH/H2O and then HCl at 65°. This methodology was similarly extended to higher (C17) and lower (C15 to C11) cyclic ketone analogues, as well as regioselectively to (-)-(R)-muscone (5c) and homomuscone (5f) (Scheme 2). Olfactive properties of the corresponding macrocyclic 1-oxaspiro[2,n]alkanes and -alkenes 4 and 8, resulting from a Coreyi-Chaykovsky oxiranylation, are also presented. Copyright
- Chapuis, Christian,Robvieux, Fabrice,Cantatore, Carole,Saint-Leger, Christine,Maggi, Laurent
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p. 428 - 447
(2012/05/07)
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- Indirect electrochemical oxidation of cyclic ketones: Influence of ring size, mediator and supporting electrolyte on the result of the reaction
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The result of the indirect electrochemical oxidation of cyclic ketones in methanol in an undivided cell in the presence of sodium halides depends on the ring size of ketone and the type of mediator. Selectivity of the reaction in some cases and current efficiency are increased by addition of supporting electrolyte - sodium hydroxide. Formation of cyclic 2,2-dimethoxycycloalkanols and the electrochemically induced Favorskii rearrangement with the formation of methyl cycloalkencarboxylates containing in the ring one carbon atom less than starting ketone are the main ways of the indirect electrochemical oxidation of cyclic ketones.
- Barba, Fructuoso,Elinson, Michail N.,Escudero, Jose,Feducovich, Sergey K.
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p. 4427 - 4436
(2007/10/03)
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- Indirect electrochemical oxidation of cyclic ketones: Strong influence of ring size on the result of the reaction
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The result of the indirect electrochemical oxidation of cyclic ketones in methanol in the undivided cell in the presence of sodium iodide depends on the ring size. Cyclopentanone affords 2,2-dimethoxycyclopentanone. While cyclohexanone gives rise 2,2-dimethoxycyclo-hexanol, and cyclic ketones with higher ring size undergo new type of the electrochemically induced Favorskii rearrangement with the formation of methyl cycloalkencarboxylates containing in the ring on the one carbon atom less than starting ketone. So the simple electrocatalytic system can distinguish the ring size of cyclic ketones.
- Barba, Fructuoso,Elinson, Michail N.,Escudero, Jose,Feducovich, Sergey K.
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p. 5759 - 5762
(2007/10/03)
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- PREPARATION OF MEDIUM- AND LARGE-SIZED CARBOCYCLES BY MEANS OF SmI2-PROMOTED INTRAMOLECULAR REFORMATSKY REACTION
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Medium- as well as large-sized carbocyclic compounds whose ring skeletons are composed entirely of sp3 carbons have been prepared in high yields under mild conditions by utilizing SmI2-promoted intramolecular Reformatsky reaction.
- Inanaga, Junji,Yokoyama, Yasuo,Handa, Yuichi,Yamaguchi, Masaru
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p. 6371 - 6374
(2007/10/02)
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