| Pentacoordinate phosphorus compounds as intermediates or transition state speciesare proposed in numerous biological processes.In this thesis,sixteen isomers of chiralbisamino acyl pentacoordinate spirophosphoranes derived from L-or D-amino acidswere synthesized and separated,respectively.To investigate the stereochemistry ofchiral bisamino acyl pentacoordinate spirophosphoranes systematically,these isomerswere characterised by high performance liquid chromatography (HPLC),nuclearmagnetic resonance (NMR),single crystal X-ray diffraction,circular dichroism (CD),electrospray ionization mass spectrometry (ESI-MS) and the theoretical calculation ofquantum chemistry.First of all,two sets of diastereoisomers of chiral bisamino acyl pentacoordinatespirophosphoranes derived from the reactions of L-or D-amino acids and PCl3.Thesediastereoisomers could be separated by achiral HPLC with the purity of 99.5%.Thesolid-state CD spectra of enantiomers displayed virtually mirror images of each other,and showed the same retention times of achiral HPLC and similar NMR spectra,respectively.The 1H-1H COSY spectra of these compounds identified an interaction between theP-H proton and theα-hydrogen of amino acids,thus establishing unusual couplingthrough four bonds for these species with 4JH-C-N-P-H 2.4 Hz.This phenomenon wasconfirmed by the theoretical calculation of quantum chemistry.For diastereoisomers,the difference of the extensional orientation of P-H and C-H bond,which result in thedifference of the 1H-1H COSY and the coupling of 4JH-C-N-P-H was 2.5 or 0.5 HzPotential epimerization of these isomers were monitored by 31p and 1H NMR at rtusing DMSO-d6 or CDCl3 as solvents to investigated the stability of these bisamino acylpentacoordinate spirophosphoranes.No epimerization was observed over a period offorty days.The high enantiopurity and good configurational stability of these isomers isessential for the following stereochemistry study.The absolute configurations of these chiral bisamino acyl pentacoordinatespirophosphoranes were proven when eight crystal structures were characterized bysingle crystal X-ray diffraction analysis.These compounds arranged in a distorted TBPgeometry.Two nitrogen atoms and a hydrogen atom form an equator plane and twooxygen atoms are in apical positions.Base on these data,we adopted the nomenclature system for coordination compound [MX(AB)2] (AB=hetero-bidentate ligand) with aTBP geometry to determine the absolute configuration of the phosphorus center.Andthen the absolute configurations of all compounds were correlated with solid-state CDand 1H NMR spectroscopy.The difference of 1JP-H and 1JP-N between the bisamino acyl pentacoordinatespirophosphoranes P(Ⅴ) and tetracoordinate phosphorus compounds P(Ⅳ) were alsodiscussed.The experimental results showed that 1JP(Ⅳ)-H (～700 Hz)＜1JP(Ⅴ)-H (～800 Hz);but 1JP(Ⅳ)-N (～41 Hz)＞1JP(Ⅴ)-N (～32 Hz).After the geometry was optimized byDFT/B3LYP/6-31+G(d,p),DFT/B3LYP/IGLOⅢwas used to calculate the 1JP-X,it isshowed that the P-N bond displayed a nature of double bond which decreased thepercent of s orbit,which resulted in the decrease of the 1JP-N value.Meanwhile,the solid-state and solution CD of bisamino acyl pentacoordinatespirophosphoranes were measured,combined with the theoretical calculations of CDspectra of bisvalinyl or bisleucinyl pentacoordinate spirophosphoranes.We propsed thatfor the bisamino acyl pentacoordinate spirophosphoranes,when the side-chain of aminoacid was a saturated fatty chain,the signs of CD was controlled by both the chirality ofphsophours atom andα-carbons of the amino acids.In addition,the electronic transitionof these compounds were also discussed.Finally,the bisamino acyl pentacoordinate spirophosphoranes were investigated byESI-MS.It was found that the MS/MS can not distinguish the chirality of compoundseffectively.In tandem mass of positive ion ([M+H]+ or [M+Na]+),the side-chain ofamino acid could stabilize the imine ion and influence the fragmentation patterns,especially the existence of phenyl ring side-chain.In tandem mass of negative ion([M-H]-) for bisphenylglycinyl pentacoordinate spirophosphoranes,the phenyl ring wasconjugated to the spiro ring,which could stabilize the fragment ions and displayeddifferent fragmentation pathways.In conclusion,the stereochemistry of chiral bisamino acyl pentacoordinatespirophosphoranes were discussed by several methods.By the theoretical calculation ofquantum chemistry,the spectra of 1H NMR and CD was explained reasonably.
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