An efficient preparation of α-diketones.

An efficient preparation of α-diketones.

Machado, Shirley Muniz; Sousa, Fabiana Garcia de; Silva, Gil Valdo José da

Abstract:

Cyclic α,β-epoxy ketones are valuable synthetic intermediates due to their high reactivity. Various products resulting from rearrangements of cyclic 2,3- epoxy ketones are important starting materials for the synthesis of perfumes, synthetic food flavorings, and pharmaceuticals. Lewis acid catalyzed ring opening of these epoxides usually follow some well defined paths: the intermediate carbocation is always formed in the carbon atom farther from the carbonyl group (III) (Scheme 1), because this group destabilizes positive charges in -position. The carbocation can either undergo acyl migration or H+ elimination (or hydrogen migration) to form a ring-contracted aldehyde (A) or an - diketone (B) (Scheme 1). Scheme 1: Lewis acid catalyzed rearrangement of cyclic 2,3-epoxy ketones.

Cyclic α,β-epoxy ketones are valuable synthetic intermediates due to their high reactivity. Various products resulting from rearrangements of cyclic 2,3- epoxy ketones are important starting materials for the synthesis of perfumes, synthetic food flavorings, and pharmaceuticals. Lewis acid catalyzed ring opening of these epoxides usually follow some well defined paths: the intermediate carbocation is always formed in the carbon atom farther from the carbonyl group (III) (Scheme 1), because this group destabilizes positive charges in -position. The carbocation can either undergo acyl migration or H+ elimination (or hydrogen migration) to form a ring-contracted aldehyde (A) or an - diketone (B) (Scheme 1). Scheme 1: Lewis acid catalyzed rearrangement of cyclic 2,3-epoxy ketones.

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DOI: 10.5151/chempro-14bmos-R0099-1

Referências bibliográficas

• [1] 1. T. –L. Ho, S.-H. Liu, Synth. Commun., 1983,13, 685.
• [2] 2. House, H. O. e Wasson, R. L.; J. Am. Chem. Soc., 1957, 79, 1488-1492.
• [3] 3. Gannon, W. F. and House, H. O.; Org. Synth, 1973, coll. vol. 5, 539.
• [4] 4. Bergman, R. e Magnusson, G.; J. Org. Chem., 1986, 51, 212-217.

Como citar:

Machado, Shirley Muniz; Sousa, Fabiana Garcia de; Silva, Gil Valdo José da; "An efficient preparation of α-diketones.", p-99-99. In: In Blucher Chemistry Proceedings, São Paulo, v. 1, n. 1, Setembro.2013. São Paulo: Blucher, 2013.
ISSN 23184043, DOI 10.5151/chempro-14bmos-R0099-1