Helicity of N,N′-diaryl-trans-1,2-diaminocyclohexane derivatives. Implications for molecular helicity manipulations
摘要:
Derivatives of trans-1,2-diaminocyclohexane (DACH), useful as chiral ligands, scaffolds and building blocks, differ in their conformation. The conformation of N,N'-diaryl-DACH derivatives was studied by the semiempirical and DFT computational methods and by exciton-coupled circular dichroism. It was found that, contrary to M-helical N,A -diimine, N,N'-diimide and N,N'-diamide derivatives, the aromatic residues in N,M-diphenyl derivatives are oriented to form a P-helix for the (R,R)-DACH absolute configuration. The helicity of the bis-aryl system is modified in the case of I-naphthyl or 2-naphthyl derivatives. Further switching of helicity has been demonstrated by either protonation or mono-N-acetylation of N,N'-diaryl DACH derivatives. (C) 2003 Published by Elsevier Ltd.
is performed under air or in the presence of an hydrogen trap. The interest of the synthesized ligands were evaluated in the reduction of aromaticketones. The alcohols were efficiently and selectively obtained with an iridium complex and a mixture of formic acid and sodium formate.
Helicity of N,N′-diaryl-trans-1,2-diaminocyclohexane derivatives. Implications for molecular helicity manipulations
作者:M Kwit、J Gawronski
DOI:10.1016/j.tet.2003.09.090
日期:2003.11
Derivatives of trans-1,2-diaminocyclohexane (DACH), useful as chiral ligands, scaffolds and building blocks, differ in their conformation. The conformation of N,N'-diaryl-DACH derivatives was studied by the semiempirical and DFT computational methods and by exciton-coupled circular dichroism. It was found that, contrary to M-helical N,A -diimine, N,N'-diimide and N,N'-diamide derivatives, the aromatic residues in N,M-diphenyl derivatives are oriented to form a P-helix for the (R,R)-DACH absolute configuration. The helicity of the bis-aryl system is modified in the case of I-naphthyl or 2-naphthyl derivatives. Further switching of helicity has been demonstrated by either protonation or mono-N-acetylation of N,N'-diaryl DACH derivatives. (C) 2003 Published by Elsevier Ltd.