A direct method for the synthesis of polyfunctionalized unsaturated carbonyl derivatives by Michael addition of nitroalkanes to enediones with the help of DBU
作者:Roberto Ballini、Giovanna Bosica
DOI:10.1016/0040-4020(95)00136-v
日期:1995.4
The Michael addition of several nitroalkanes to dimethyl maleate, (Z)-3-hexene-2,5-dione, N-ethyl maleimide, and N-phenyl maleimide, in MeCN or THF, proceeds very efficiently on DBU as base, and furnishes good to high yields of polyfunctionalized unsaturated carbonyl derivatives.
Nitrocyclopropane formation has been successfully carried outby reaction of bromonitromethane with electrophilic alkenes bearingtwo electron-withdrawing groups in the α- and β-positions,and in the presence of potassium carbonate as base. The method allowsgood yields and moderate to satisfactory diastereoselectivity withlinear alkenes, while shows the complete formation of the exo-product with N-alkylmaleimides.
We report a highly efficient and selective catalytic system, ABNO (9-azabicyclo-[3.3.1]nonane N-oxyl)/HNO3, for the aerobic oxidation of substituted furans to cis-2-ene-1,4-diones under mild reaction conditions using oxygen as the oxidant. The catalyst system is amenable to various substituted (mon-, di-, and tri-) furans and tolerates diverse functional groups, including cyano, nitro, naphthyl, ketone
我们报告了一种高效和选择性催化体系 ABNO (9-azabicyclo-[3.3.1] nonane N -oxyl)/HNO 3,用于将取代的呋喃有氧氧化为顺式-2-ene-1,4-二酮以氧气为氧化剂,反应条件温和。该催化剂体系适用于各种取代的(单-、二-和三-)呋喃,并耐受多种官能团,包括氰基、硝基、萘基、酮、酯、杂环,甚至甲酰基。基于对照和18个O标记实验,提出了氧化的可能机理。
Synthesis of Diacetal Trioxa-cage Compounds via Reaction of Bicyclo[2.2.1]heptenes and Bicyclo[2.2.2]octenes with Dimethyldioxirane
作者:Hui-Chang Lin、Hsien-Jen Wu
DOI:10.1016/s0040-4020(99)00997-7
日期:2000.1
A new entry for the synthesis of diacetal trioxa-cage compounds via oxirane-induced sequential cyclization reaction of 2,3-bis-endo-diacylbicyclo[2.2.1]-5-heptenes and 2,3-bis-endo-diacylbicyclo[2.2.2]-5-octenes is reported. In the case of bicyclo[2.2.2]octenes, sequential cyclization reaction induced by iodine as electrophile failed. We have also demonstrated that dimethyldioxirane can selectively
5-disubstituted dihydrofurans. Hydrolysis of electrooxidation products with ion enchange-resin, followed by the treatment with base gave rethrolones. Furthermore, this method was applicable for the synthesis of 2-alkyl-4-hydroxycyclopentenone.