<i>In</i> <i>situ</i> preparation of cyclopropanones with the bicyclo[3.1.0]hexan-6-one skeleton (substituted examples of the Loftfield intermediate). Confirmation of a very facile intramolecular alkyl cyclopropanone – dienol rearrangement
作者:T. S. Sorensen、F. Sun
DOI:10.1139/v96-010
日期:1996.1.1
low-temperature 1H and 13C NMR spectroscopy. The1,5-di-tert-butyl and 1-tert-butyl analogs were thermally stable to ca. 0 °C, but the 1-tert-butyl-5-methyl and 1-tert-butyl-5-ethyl derivatives were extremely labile, rearranging at ca. −80 °C into a cross-conjugated enol, where the methyl (or ethyl) substituent was converted into an exomethylene group. These enols were also characterized as in situ species using 1H
从相应的 2,6-二溴环己酮开始,用有机金属盐 PPN+Cr(CO)4NO− 还原去除溴原子,原位制备了四种取代的双环 [3.1.0] 己酮(环丙酮)。在 -78 或 -100 °C 下基本上是瞬时的,并且可以方便地在 NMR 管中进行,以便通过低温 1H 和 13C NMR 光谱轻松表征产品。1,5-二叔丁基和 1-叔丁基类似物的热稳定性达到约 0 °C,但 1-叔丁基-5-甲基和 1-叔丁基-5-乙基衍生物极不稳定,重排约 -80 °C 转化为交叉共轭的烯醇,其中甲基(或乙基)取代基转化为外亚甲基。这些烯醇还使用 1H 和 13C NMR 光谱表征为原位物种,并通过让烯醇 → α,β-不饱和酮重排发生在约 25 °C。使用 1-叔丁基-5-CD3 类似物研究了烯醇形成的机制,并且...