Photoinduced molecular transformations. Part 130. Novel stereospecific photorearrangement and stereospecific addition of methanol in steroidal α,β-unsaturated cyclic ketone oximes
作者:Hiroshi Suginome、Makoto Kaji、Toshiharu Ohtsuka、Shinji Yamada、Takashi Ohki、Hisanori Senboku、Akio Furusaki
DOI:10.1039/p19920000427
日期:——
products in both of these photoreactions and no lactams were formed. Deuterium-labelling studies on the photoreactions of 5α-cholest-1-en-3-one oxime and its trideuteriated derivative established that a deuteron or a proton is stereospecifically introduced at the 2α-position of the Steroidal oxime in this photorearrangement. A pathway which involves an unprecedented stereospecific addition of a proton or
在质子或非质子传递溶剂中辐照5α-胆甾-1-烯-3-酮肟或其4,4-二甲基衍生物得到4'α,5'-dihydro-4-nor-5α-cholest-1-eno [2,1- c]异恶唑或相应的3,3-二甲基衍生物,它是由空前的光重排引起的。前者的分子结构通过X射线晶体学分析确定。1β-甲氧基-5α-胆甾醇-3-酮肟或它们的4,4-二甲基衍生物是甲醇在烯酮肟双键上空前的光加成反应,是这些光反应的伴随产物,没有内酰胺形成。对5α-胆甾-1-烯-3-酮肟及其三氘代衍生物的光反应的氘标记研究表明,在该光重排中,将氘酮或质子立体定向引入类固醇肟的2α位。涉及到光生质子或氘核前所未有的立体定向添加的途径,关于从激发的肟形成异恶唑,提出了从后侧肟的双键扭转,随后的所得碳阳离子断裂和亚硝酸盐中间体的分子内1,3-偶极加成的方法。氘标记研究还确定,在肟的双键中添加甲醇也是立体定向的。根据标记研究得出的结论是,甲醇的光加成机理涉及立体特异性