1. SYNTHESIS, CRYSTAL STRUCTURE, AND DIASTREREOMERIC TRANSFER OF PENTACOORDINATED PHOSPHORANES CONTAINING VALINE OR ISO-LEUCINE RESIDUE.
- Author
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Hua Fu, Jing-Hua Xu, Ru-Ji Wang, Zhong-Zhou Chen, Guang-Zhong Tu, Qin-Zhu Wang, and Yu-Fen Zhao
- Subjects
VALINE ,LEUCINE ,AMINO acids ,CRYSTALLOGRAPHY ,NUCLEAR magnetic resonance spectroscopy ,CHEMICAL reactions - Abstract
Pentacordinated phosphoranes containing valine or iso-leucine residue (2-phenyl-2, 75-spiro[1,3,2-phenanthrodioxaphosphole-2,2'-1,3,2-oxazaphospholan]-5';-one)were synthesized through sequential two-step reactions, whereby the reaction products of phenyldichlorophosphine with N,O-bis(trimethylsilyl)valine or iso-leucine were followed by the addition of phenanthrenequione, and the crystals of 4a and 4b were obtained from benzene and hexane mixed solution. The x-ray structure of the crystals 4a and 4b revealed that they are distorted TBP, exhibiting R[subp] absolute configuration. The 31[subP] NMR spectra showed that the S[subp] diastereomer could transfer into the other one R[subp] that came out from the solution during crystallization. Correspondingly, when it was dissolved in solvents the Re diastereomer transferred into the other one S[subp], and the pair of diastereomers changed each other in solution at room temperature through a phosphonium carboxylate zwitterions intermediate. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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