Highly Regio- and Stereoselective Intramolecular Rearrangement of Glycidol Acetal to Alkoxy Cyclic Acetals
作者:Meera Johny、Rose Mary Philip、Goreti Rajendar
DOI:10.1021/acs.orglett.2c02397
日期:2022.8.26
Lewis acid activation of acetal generates an oxocarbenium ion that initiates the epoxide ring-opening event, giving the bicyclic [3,1,0]epoxonium ion intermediate that undergoes exo/endo-selective opening by a tethered alkoxide. Mechanistic insights into preferential acetal activation over the epoxide were obtained by crossover experiments. The method was applied in the total synthesis of parvistone
Indium-Promoted Chemo- and Diastereoselective Allylation of α,β-Epoxy Ketones with Potassium Allyltrifluoroborate
作者:Farhad Nowrouzi、John Janetzko、Robert A. Batey
DOI:10.1021/ol1023757
日期:2010.12.3
A practical method for the chemo- and diastereoselective allylation of alpha,beta-epoxy ketones has been developed by using the convenient air and moisture stable reagent potassium allyltrifluoroborate. Indium metal was found to promote addition in stoichiometric or catalytic amounts, to afford alpha,beta-epoxyhomoallylic tertiary alcohols in high yields and diastereoselectivities, without competing ring-scission of the epoxide.
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作者:S. Servi、A. Cansiz、A. Acar、M. Koparir
DOI:10.1023/a:1013843700623
日期:——
Substituted 1,5-hexadien-3-ols were synthesized by the [2,3]-Wittig rearrangement of unsymmetrical bis-allyl ethers, as well as by reactions of 1-(2-alkenyl)-2-chloromethyloxiranes with Mg/THF. The products were oxidized with pyridinium chlorochromate (PCC), zinc chlorochromate (ZCC), tert-butyl hydroperoxide in the presence of OsO4, and tent-butyl hydroperoxide alone. The oxidation of substituted 1,5-hexadien-3-ols with PCC and ZCC gave the corresponding carbonyl compounds. In the reaction with tertbutyl hydroperoxide catalyzed by OsO4 the internal double bond in the substrate was regioselectively converted into epoxy group, whereas allylic oxidation was prevented.