Utente:Grasso Luigi/sanbox1/Ossidazione di Corey–Kim
L'ossidazione di Corey–Kim è una reazione di ossidazione usata per sintetizzare aldeidi e chetoni da alcool primari e secondari.[1][2][3][4][5]
Tale reazione prende il nome dal chimico Americano e Nobel Elias James Corey e da chimico Coreano-Americano Choung Un Kim.
Anche se l'ossidazione di Corey–Kim possiede il distintivo vantaggio rispetto l'ossidazione di Swern di potersi effettuare sopra –25 °C, non è così comunemente usata a causa di problemi di selettività nei substrati suscettibili alla clorazione di N-clorosuccinimide.
Meccanismo della reazione
modificaDimethyl sulfide (Me2S) is treated with N-chlorosuccinimide (NCS), resulting in formation of an "active DMSO" species that is used for the activation of the alcohol. Addition of triethylamine to the activated alcohol leads to its oxidation to aldehyde or ketone and generation of dimethyl sulfide. In variance with other alcohol oxidation using "activated DMSO," the reactive oxidizing species is not generated by reaction of DMSO with an electrophile. Rather, it is formed by oxidation of dimethyl sulfide with an oxidant (NCS).
Under Corey–Kim conditions allylic and benzylic alcohols have a tendency to evolve to the corresponding allyl and benzyl chlorides unless the alcohol activation is very quickly followed by addition of triethylamine. In fact, Corey–Kim conditions —with no addition of triethylamine— are very efficient for the transformation of allylic and benzylic alcohols to chlorides in presence of other alcohols.
Variazioni
modificaSubstituting dimethyl sulfide with something less noxious has been the goal of several research projects. Ohsugia et al.[6] substituted a long-chain sulfide, dodecyl methyl sulfide, for dimethyl sulfide. Crich et al.[7] utilized fluorous technology in a likewise manner.
Voci correlate
modificaNote
modifica- ^ (EN) E. J. Corey; C. U. Kim, New and highly effective method for the oxidation of primary and secondary alcohols to carbonyl compounds, in J. Am. Chem. Soc., vol. 94, n. 21, 1972, pp. 7586–7587, DOI:10.1021/ja00776a056.
- ^ (EN) E. J. Corey; C. U. Kim, A method for the oxidation of sec,tert-1,2-diols to α-hydroxy ketones without carbon-carbon cleavage, in Tetrahedron Lett., vol. 15, n. 3, 1974, pp. 287–290, DOI:10.1016/S0040-4039(01)82195-X.
- ^ (EN) S. Katayama; K. Fukuda; T. Watanabe; M. Yamauchi, Synthesis of 1,3-Dicarbonyl Compounds by the Oxidation of 3-Hydroxycarbonyl Compounds with Corey–Kim Reagent, in Synthesis, vol. 1988, 1988, pp. 178–183, DOI:10.1055/s-1988-27506.
- ^ (EN) T. T. Tidwell, Oxidation of Alcohols by Activated Dimethyl Sulfoxide and Related Reactions: An Update, in Synthesis, vol. 1990, 1990, pp. 857–870, DOI:10.1055/s-1990-27036.
- ^ (EN) J. T. Pulkkinen; J. J. Vepsäläinen, 3-Unsubstituted 1,5-Diaryl-2,4-pentanediones and -4-methoxy-2-pentanones: Synthesis via Corresponding 3-Hydroxy Ketones Generated from 2-Isoxazolines, in J. Org. Chem., vol. 61, n. 24, 1996, pp. 8604–8609, DOI:10.1021/jo960887a.
- ^ Ohsugia, S.-I.; Nishidea, K.; Oonob, K.; Okuyamab, K.; Fudesakaa, M.; Kodamaa, S.; Node, M. Tetrahedron 2003, 59, 8393–8398.
- ^ Crich, D.; Neelamkavil, S. Tetrahedron 2002, 58, 3865–3870.
Collegamenti esterni
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