- Stereoselective P-Cyclisation and Diastereoisomeric Purification of 5-Phenyl-3-(pyridin-2-yl)-1,3,2-oxazaphospholidine Formed from a Thermolabile Protecting Group
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A one-pot, two-step synthesis of 5-phenyl-3-(pyridin-2-yl)-1,3,2-oxazaphospholidine from linear precursor bis(diisopropylamino){2-[(pyridin-2-yl)amino]-1-phenylethoxy}phosphine is achieved using a stereoselective intramolecular cyclisation. Application of a pure enantiomer {1-phenyl-2-[(pyridin-2-yl)amino]ethanol} enabled partial diastereopurification by crystallisation. For all four diastereoisomers, the absolute configuration of the P-centre was determined using X-ray crystallography and correlative 31P NMR data. Stereochemically pure 5a was then used in nucleoside phosphitylation reactions with partial loss of stereopurity by retention of configuration on the phosphorus centre. A one-pot, two-step synthesis of 5-phenyl-3-(pyridin-2-yl)-1,3,2-oxazaphospholidine from linear bis(diisopropylamino){2-[(pyridin-2-yl)amino]-1-phenylethoxy}phosphine by stereoselective intramolecular P-cyclisation is described. For all four diastereoisomers produced, the absolute configuration of the P-centre is determined by X-ray crystallography and correlated with 31P NMR data.
- Kaczyński, Tomasz P.,Manszewski, Tomasz,Chmielewski, Marcin K.
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p. 2522 - 2527
(2016/06/01)
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- Engineering N-(2-pyridyl)aminoethyl alcohols as potential precursors of thermolabile protecting groups
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Crystal and NMR analyses of four precursors of N-(2-pyridyl) thermolabile protecting group (TPG) were carried out. Two torsion angles have been identified as indicators that predict the molecules' thermolabile properties. Conformation that minimizes the N1...C8 distance is crucial for thermocyclisation. Nucleophilicity of the pyridyl ring is the driving force for the reaction but it is insufficient for thermocyclisation which is dominated by the molecules' ability to adopt a favourable conformation. The pKa value was recorded for all analyzed N-(2-pyridyl)aminoethyl alcohols. However, its effect is small in the determination of thermolability. Based on the analysis that we carried out, N-benzyl N-(2-pyridyl)aminoethyl was selected as a potential precursor of thermolabile carbonate of TPG. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
- Chmielewski, Marcin K.,Tykarska, Ewa,Markiewicz, Wojciech T.,Rypniewski, Wojciech
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experimental part
p. 603 - 612
(2012/05/04)
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- ON THE REACTION OF PHENYLGLYOXAL WITH 2-AMINOPYRIDINE
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A structure of 2-phenyl-1H-imidazopyridinium-3-olate (1) has been assigned to the product of the title reaction instead of the previously reported one.In solution, 1 undergoes photo-oxidation related to that occurring in Cypridina luciferine.
- Alcaide, Benito,Perez-Ossorio, Rafael,Plumet, Joaquin,Sierra, Miguel A.
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p. 1627 - 1630
(2007/10/02)
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