Synthesis of Enantiomerically and Diastereomerically Pure 4-Hydroxy-1,2-alkadienyl Carbamates and Their Application in a Modified Nazarov Cyclization Towards Chiral Cyclopentenones
作者:Dieter Hoppe、Maik Zimmermann、Birgit Wibbeling
DOI:10.1055/s-2004-816002
日期:——
The addition of racemic titanated alkynyl N,N-diisopropylcarbamates onto enantiopure α-dibenzylamino- or a-silyloxyalkanals affords two (out of four possible) diastereomeric, enantiopure 5-hetero-substituted 4-hydroxy-1,2-alkadienyl carbamates. As demonstrated for hydroxyallenes 23 and 24, the reaction sequence for modified Nazarov cyclization according to Tius, yields stereohomogeneous, highly substituted
将外消旋的钛化炔基 N,N-二异丙基氨基甲酸酯添加到对映纯的 α-二苄基氨基-或α-甲硅烷氧基链烷醛上,得到两种(四种可能的)非对映体、对映纯 5-杂取代的 4-羟基-1,2-链二烯基氨基甲酸酯。正如羟基丙二烯 23 和 24 所证明的,根据 Tius 进行改性 Nazarov 环化的反应序列产生立体均相、高度取代的 5-亚烷基-2,3-二烷基-4-苯基-2-环戊烯-1-酮 (Z,R) -25 和 (E, R)-26。