Chemoenzymatic Asymmetric Total Synthesis of Phosphodiesterase Inhibitors: Preparation of a Polycyclic Pyrazolo[3,4-<i>d</i>]pyrimidine from an Acylnitroso Diels−Alder Cycloadduct-Derived Aminocyclopentenol
作者:May Xiao-Wu Jiang、Namal C. Warshakoon、Marvin J. Miller
DOI:10.1021/jo0484070
日期:2005.4.1
Enzymatic resolution of Boc-protected 4-aminocyclopenten-1-ol 4c gave both enantiomers 5c and 6c in high ee. Boc removal and separate condensation with chloropyrazolopyrimidine 18 provided elaborated 1,4-aminocyclopentenol derivatives 20 and 26, respectively. Separate treatment of 20 and 26 with Pd(0) under basic conditions induced cyclization to unsaturated polycycles 22 and 27, which, upon catalytic
Boc保护的4-氨基环戊烯-1-醇4c的酶解得到了高ee值的对映体5c和6c。Boc的去除和与氯吡唑并嘧啶18的单独缩合分别提供了详细的1,4-氨基环戊烯醇衍生物20和26。在碱性条件下用Pd(0)分别处理20和26诱导环化为不饱和多环22和27,在催化氢化后将其转化为新的含环戊烷的吡唑并嘧啶24和28,是最近描述的新型磷酸二酯酶抑制剂的类似物。