engleski

New strategy for the semi~protection ofpolyols. Diphenyldisulfone as neutral catalyst for the chemoselective cleavage of methyl substituted allyl ethers

Protection and deprotection of alcohols is a central theme of organic chemistry. Sophisticated synthetic schen1e may fail because of protective groups that cannot be ren1oved under suitable conditions without product decomposition. We found that in the presence of a catalytical a1nount of diphenyldisulfone, methallyl, prenyl and methylprenyl ethers are cleaved readily, the fastest reaction occurring with the most substituted allyl systems, whereas allyl ethers are not affected. These reactions are due to the benzenesulfonyl radical engendered by thermal ho1nolysis of (PhS02)2. This discovery permits the cleavage of alkyl substituted allyl ethers under neutral conditions, without heavy metals and with a useful reactivity sequence, i.e.: methylprenyl > prenyl > methallyl >> allyl. Furthermore, other protected alcohols such as silyl ethers, esters and benzyl ethers are not affected other these conditions.

SO2, deprotection, allyl ethers, radicals

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