A Formal Total Synthesis of (-)-Cephalotaxine.
作者:Masaszumi IKEDA、Serry A.A. EL BIALY、Ken-ichi HIROSE、Miho KOTAKE、Tatsunori SATO、Said M.M. BAYOMI、Ihsan A. SHEHATA、Ali M. ABDELAL、Laila M. GAD、Takayuki YAKURA
DOI:10.1248/cpb.47.983
日期:——
A formal total synthesis of (-)-cephalotaxine (1) has been achieved. The key step is an intramolecular aldol condensation of the diketone 9, which in turn was obtained in three steps from the azabicyclic compound 6 derived from D-proline according to Seebach's procedure. Treatment of 9 with a catalytic amount of sodium 2-methyl-2-butanolate in benzene at room temperature gave the alpha, beta-unsaturated
(-)-头孢他辛(1)的正式合成已经完成。关键步骤是二酮9的分子内醇醛缩合,其又按照Seebach的方法从衍生自D-脯氨酸的氮杂双环化合物6中分三步得到。在室温下用催化量的2-甲基-2-丁醇钠的苯催化处理9,得到α,β-不饱和酮8,产率为43%。催化氢化8,然后用硼氢化钠还原酮22,并将所得醇23乙酰化,得到乙酰氧基衍生物24,在脱保护后,用(甲硫基)乙酸酰化得到酰胺26。将化合物26转化继开发用于合成外消旋化合物的合成操作后,生成旋光的酮内酰胺4。