Intramolecular photocycloadditions-cyclobutane fragmentation: total synthesis of (.+-.)-pentalenene, (.+-.)-pentalenic acid, and (.+-.)-deoxypentalenic acid
作者:Michael T. Crimmins、Joe A. DeLoach
DOI:10.1021/ja00264a037
日期:1986.2
Pentalenene, pentalenic acid, and deoxypentalenic acid, important metabolites in the biosynthesis of the pentalenolactones, have been synthesized from methyl isobutyrate through a common intermediate. The initial key step involves a novel conjugate addition-cycloacylation sequence on an acetylenic diester. The 1,6-diene which results is converted in two steps to a 1,6-diene diester which undergoes
戊烯、戊烯酸和脱氧戊烯酸是戊烯内酯生物合成中的重要代谢物,它们是由异丁酸甲酯通过常见中间体合成的。最初的关键步骤涉及乙炔二酯上的新型共轭加成环酰化序列。得到的 1,6-二烯分两步转化为 1,6-二烯二酯,该二酯经过高度立体选择性光环加成以设置三个必要的立体中心。一个环丁烷键的还原裂解产生一个功能化的螺双环 (4.4) 壬酮,它在三个步骤中被转化为二酮 10,即关键的中间体。该系统的差异化功能化为戊烯、戊烯酸和脱氧戊烯酸提供了高效、立体控制的途径,所有这些途径均呈外消旋形式。