Unusual Totally Selective Cyclodimerization of Epoxides: Synthesis of a Pair of Diastereoisomers of Enantiopure 2,5-Disubstituted-1,4-Dioxanes withC2 Symmetry
作者:José M. Concellón、Pablo L. Bernad、Virginia del Solar、Santiago García-Granda、M. Rosario Díaz
DOI:10.1002/adsc.200700486
日期:2008.2.22
The synthesis of the C2-symmetrical (2R,5R)- and (2S,5S)-2,5-bis-[(S)-1-(dibenzylaminoalkyl)]-1,4-dioxanes 1 or 2 in enantiopure form is reported. Compounds 1 and 2 were obtained by a completely selective and unusual cyclodimerization of chiral (2R,1′S)- or (2S,1′S)-2-(1-aminoalkyl)epoxides 3 or 4 promoted by a mixture of diisopropylamine and boron trifluoride⋅diethyl etherate complex. The structure
所述的合成Ç 2 -symmetrical(2 - [R,5 - [R )-和(2小号,5小号)-2,5-双- [(小号)-1-(dibenzylaminoalkyl)] - 1,4-二恶烷1或报告了2个对映体纯形式。化合物1和2是通过手性(2 R,1 'S)-或(2 S,1 'S)-2-(1-氨基烷基)环氧化合物3或4的完全选择性和异常环二聚获得的由二异丙胺和三氟化硼·二乙基醚配合物的混合物促进。通过单晶X射线衍射分析确定所获得的二恶烷的结构。已经提出了一种机制来解释这种转变。