A mild and efficient copper-catalyzed trifluoromethylation reaction which involves the cyclization of oximes has been developed. This method provides a convenient access to a variety of useful CF3-containing 4,5-dihydroisoxazoles by constructing a C–CF3 bond and a C–O bond in one step.
A palladium-catalyzed efficient synthesis of 5-methylisoxazoles via oxime-mediated functionalization of unactivatedolefins is described. The reaction affords a variety of 5-methylisoxazoles in moderate to good yields. To further demonstrate the utility of the method, the rapid synthesis of valdecoxib and oxacillin is reported.
Transition-metal-free oxychlorination of alkenyl oximes: in situ generated radicals with tert-butyl nitrite
作者:Xiao-Wei Zhang、Zu-Feng Xiao、Mei-Mei Wang、Yan-Jun Zhuang、Yan-Biao Kang
DOI:10.1039/c6ob01374k
日期:——
Oxychlorination of alkenyl oximes is harder compared to the analogous oxybromination or oxyiodination because of the difficulty associated with the formation of chlorine cations or radicals. A transition-metal-free oxychlorination of alkenyl oximes has been developed, using t-BuONO as a dual oxidant and AlCl3 as a chlorine source. This convenient and practical method has been used to construct chloroisoxazolines
A highly efficient manganese-promoted oxidative cyclization of unsaturated oximes to afford the corresponding 4,5-dihydroisoxazoline alcohols was developed. A very low loading (generally 0.1–0.2 mol-%) of Mn(acac)3 (acac = acetylacetonate) promoted the oxidative cyclization through the direct incorporation of molecular oxygen present in air (open flask) at room temperature.
Ruthenium-Catalyzed Direct Transformation of Alkenyl Oximes to 5-Cyanated Isoxazolines: A Cascade Approach Based on Non-Stabilized Radical Intermediate
A convenient method offers an easy access to 5‐cyanated isoxazolines in good to high yields and shows good functional group tolerance and high efficiency. In this protocol, tert‐butyl nitrte plays a dual role, acting as an oxidant as well as a nitrogen source. Remarkably, this new reaction avoids using any toxic radical initiator or cyanide reagents and constructs C–O and C≡N triple bonds in a single‐step