- Green Organocatalytic Dihydroxylation of Alkenes
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An inexpensive, green, metal-free one-pot procedure for the dihydroxylation of alkenes is described. H2O2 and 2,2,2-trifluoroacetophenone were employed as the oxidant and organocatalyst, respectively, in this highly sustainable protocol in which a variety of homoallylic alcohols, aminoalkenes, and simple alkenes were converted into the corresponding polyalcohols in good to excellent yields. This process takes advantage of an epoxidation reaction followed by an acidic treatment in which water participates in the ring opening of the in situ prepared epoxide to lead to the desired product.
- Theodorou, Alexis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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p. 1502 - 1509
(2017/04/01)
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- Dibutyltin oxide mediated diastereoselective cyclodehydration/sulfonylation of 1,2,4-triols
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Dibutyltin oxide (Bu2SnO) mediated cyclodehydration or sulfonylation of 1,2,4-triols is predictably diastereoselective depending on the steric bulk of the substituents at C4. A larger difference (ΔA-value >1 kcal/mol) leads to the syn-1,2,4-triols favouring cyclodehydration (78-85%) to form 3-hydroxytetrahydrofurans, with the anti-1,2,4-triols favouring monosulfonylation (66-87%). Triols from symmetrical ketones preferentially undergo cyclodehydration in high yield (>75%) due to a gem-disubstituent effect. Thus, the 1,2,4-triols derived from simple cyclic ketones also favour cyclodehydration to form spirocyclic 3-hydroxytetrahydrofurans in 72-79% yields.
- Gamedze, Makhosazana P.,Nkambule, Comfort M.
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supporting information
p. 1825 - 1829
(2015/03/30)
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