Oxyfunctionalization of ketones bearing α-methylene group with piperidine oxoammonium salt.Synthesis of α-diketones from monoketones

A facile method for the title transformation is described. The reaction of 2,2,6,6-tetramethyl-4-methoxypiperidine oxoammonium chloride (1b) and ketones bearing a-methylene group in acetonitrile proceeded smoothly to give the a-oxyfunctionalized coupling products (6a-h). These coupling products decomposed upon heating in acidic medium to produce a-diketones (7a-h) in good to excellent yields.

毛裂蜂斗菜中的1个新的倍半萜化合物

目的 研究菊科蜂斗菜属植物毛裂蜂斗菜Petasites tricholobus全草中倍半萜类化学成分。方法 采用正相硅胶、反相硅胶、葡聚糖凝胶、微孔树脂等多种柱色谱填料进行分离纯化,并运用MS、NMR、UV、IR等现代波谱分析技术对化合物结构进行鉴定。结果 从毛裂蜂斗菜50%乙醇提取物中分离得到5个倍半萜类化合物,分别鉴定为1α-(cismethylthioacryloyloxy)-8α-angeloyloxy-3β,4β-epoxy-bisabola-7(14),10-diene(1)、bakkenolide IIIb(2)、monoketone(3)、japonipene C(4)和petatewalide A(5)。结论 化合物1为新化合物,命名为毛裂蜂斗菜素;化合物2~5均为首次从毛裂蜂斗菜中分离得到。