Synthesis of 1,2-Dioxolanes by Annulation Reactions of Peroxycarbenium Ions with Alkenes
摘要:
The annulation reactions of alkenes with peroxycarbenium ions enable the synthesis of a variety of functionalizable 1,2-dioxolanes. Triethysilyl-protected peroxycarbenium ions proved to be optimal for the annulation reaction. Using this method, plakinic acid analogues can be synthesized in three steps from the corresponding ketone and alkene.
ketones and aldehydes with iodine as a catalyst was studied. Ketones reacted with 30% aq hydrogen peroxide in the presence of 10 mol % of iodine to yield gem-dihydroperoxides in acetonitrile and hydroperoxyketals in methanol. The yield of hydroperoxidation of various cyclic ketones was 60−98%, including androstane-3,17-dione, while acyclic ketones were converted with a similar efficiency. Aromatic aldehydes
以碘为催化剂,研究了酮和醛的过氧化反应。酮在10摩尔%的碘存在下与30%的过氧化氢水溶液反应,生成乙腈中的宝石二氢过氧化物和甲醇中的氢过氧缩酮。包括雄甾烷-3,17-二酮在内的各种环状酮的加氢过氧化产率为60-98%,而无环酮的转化效率相近。芳香醛也可以在乙腈中以过氧化氢和碘为催化剂,转化为宝石二氢过氧化物,在甲醇中转化为氢过氧缩醛,而脂肪族醛的反应性与未催化反应相同。叔-丁基氢过氧化物以类似方式反应,得到相应的过醚衍生物。还对二氢过氧化的相对动力学进行了研究,根据该动力学,Hammet方程给出的反应常数(ρ)为-2.76,这表明过渡态中强烈的正电荷发展以及再杂交在氢过氧半水合物向宝石转化中的重要作用-二氢过氧化物。在乙腈中,碘催化剂显然能够区分消除羟基,甲氧基和氢过氧基与将水,甲醇和H 2 O 2加至羰基之间。
Triflic Acid-Functionalized Silica-Coated Magnetic Nanoparticles as a Magnetically Separable Catalyst for Synthesis of gem-Dihydroperoxides
Triflicacid-functionalizedsilica-coatedmagneticnanoparticles [γ-Fe2O3@SiO2-TfOH] were readily prepared and identified as an effictive catalyst for the transformation of aldehydes or ketones into their corresponding gem-dihydroperoxides with 30% aqueous hydrogen peroxide. The catalyst was easily separated by magnetic decantation and the recovered catalyst was reused for seven cycles without significant
A new efficient dihydroperoxidation protocol of a wide variety of carbonyl compounds with molecularoxygen, anthracene, and 2-propanol underlightirradiation afforded their corresponding gem-dihydroperoxides in high yields.
gem-Dihydroperoxides were easily obtained from the corresponding carbonyl compounds in high yields through a catalyst-free method with aqueous H2O2 (35%) in 1,2-dimethoxyethane at room temperature.
Iodine has been shown to be an efficient catalyst for the selective dihydroperoxidation of ketones with aqueous hydrogen peroxide. Ketones were directly converted to their corresponding gem-dihydroperoxides using a "green" oxidant (30% aq H2O2) and a simple catalyst ( iodine) under neutral conditions in acetonitrile. The yield of hydroperoxidation of various cyclic ketones was 60-98% including androstane- 3,17-dione, and acyclic ketones were converted with a similar efficiency.