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|Type:||Artigo de periódico|
|Title:||An approach to the construction of the carbon skeleton of marine nor-sesquiterpenes. Total synthesis of (+/-)-dehalo-napalilactone|
|Abstract:||We disclose herein a synthetic approach for the preparation of an unusual carbon skeleton, which was found in nor- sesquiterpenes isolated from marine corals. The main structural feature of this skeleton is the presence of two contiguous quaternary centers, one of them bears a spiro gamma -butyrolactone moiety. One of the quaternary centers was prepared with moderate stereoselectivity by the conjugate addition of lithium dimethylcuprate to 2-methylcyclohexenone, followed by the trapping of the intermediate enolate with allyl bromide to furnish trans-2- allyl-2,3-dimethylcyclohexan-2-one, as a major diastereoisomer. The preparation of the quaternary centers bearing the spiro gamma -butyrolactone moiety was secured by the addition of a suitably functionalized organolithium reagent on trans-2-allyl-2,3-dimetylcyclohexan-2-one, followed by separation of the isomers and two oxidation steps. This strategy has permitted us to report the racemic total synthesis of a non-natural nor-sesquiterpene derivative, in 6 steps and 16% overall yield, from 2-methylcyclohexenone.|
marine natural products
|Editor:||Soc Brasileira Quimica|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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