22082-71-9Relevant academic research and scientific papers
Solid-phase synthesis of oligodeoxyribonucleotides without base protection utilizing o-selective reaction of oxazaphospholidine derivatives
Oka, Natsuhisa,Maizuru, Yukihiro,Shimizu, Mamoru,Wada, Takeshi
experimental part, p. 144 - 154 (2011/08/05)
A study on the development of a novel method to synthesize oligodeoxyribonucleotides without base protection is described. We found that nucleoside 3′-O-oxazaphospholidine derivatives exclusively react with the hydroxy group of nucleosides in the presence
α-Fluorinated cyclic amidophosphite ligands. Their synthesis, Rh complexes and catalytic activity in the hydroformylation of styrene
Artyushin, Oleg,Odinets, Irina,Goryunov, Evgenii,Fedyanin, Ivan,Lyssenko, Konstantin,Mastryukova, Tatyana,R?schenthaler, Gerd-Volker,Kégl, Tamás,Keglevich, Gy?rgy,Kollár, László
, p. 5547 - 5559 (2007/10/03)
The synthetic approaches to cyclic phosphite and amido(diamido)phosphite ligands bearing the residues of electron withdrawing perfluorinated tails at the β-position to the phosphorus atom have been elaborated. Catalytic systems based on rhodium complexes
Sterically Congested Molecules: 2,2'-bis
Pastor, Stephen D.,Rodebaugh, R. K.,Odorisio, Paul A.,Pugin, Benoit,Rihs, Grety,Togni, Antonio
, p. 1175 - 1193 (2007/10/02)
The original suggestion that a through-space mechanism was operative in the seven-bond J(P,P) coupling constant of 30.3 Hz observed for 3,3'-bis(1,1-dimethylethyl)-2,2'-bis(oxy)>bis (1a) was investigated.In the solid-state CP-MAS 31P-NMR spectrum of 1a, two nonequivalent P-atoms were observed; sufficient resolution could not be obtained to determine whether P,P coupling was present.The preparation and spectral data of the N-methyl analogue 1b and of the acyclic N-isopropyl analogue 6 (Scheme 1) provided evidence that a) the essentially exclusive formation (R*,R*,S*)-1a in the reaction of the disodium biphenydiolate 3a with the phosphorochloridite 4a is the result of significant differences in the free energy of activation (ΔG*) for the formation of the various diastereoisomers due to the steric congestion within the molecule and that b) the magnitude of the observed P,P coupling is dependent upon the degree of conformational freedom within the molecule.In the 31P-NMR spectrum of the P-disulfide 7, which was prepared by the reaction of 1a with sulfur, 2s resonances were observed that strongly suggested that the lone electrons pair on P are involved in the mechanism for the transmission of the coupling data.The chiral analogues (4S,5R)-12 and (4R,5S)-12 of 1a were prepared in a three-step reaction sequence starting from the corresponding enatiomerically pure norephedrine 8 (Scheme 2).Both (4S,5R)- and (4R,5S)-12 were obtained as a diastereoisomer mixture that differ by the configuration of the axis of chirality, i.e., (R*,R*,R*)- and (R*,S*,R*)-12 were obtained.The major diastereoisomer was obtained upon recry stallization, and the atropisomers were observed to equilibrate in solution by monitoring the H-C(5) resonance in the 1H-NMR with time (ΔG0 = 0.4 kcal/mol; Fig. 2).The process observed corresponds to the restricted rotation about the central single bond of the biphenyl system.The isolation of an atropisomer with only a single ortho substituent on each aryl ring is quite rare.In the 13C-NMR spectrum of both (R*,R*,R*)- and (R*,S*,R*)-12, C(5) is two-bond-coupled to the oxazaphospholidine P-atom (2J(C(5),P((2)) = 8.5 Hz) that is further virtually coupled to the P-atom of the other oxazaphospholidine ring (7J(P(2),P(2')) = 30 Hz: 9J(C(5),P(2')) = 0 Hz; δ(P(2)) = δ(P(2')) = 136 ppm).In the 31P-NMR spectrum of (R*,R*,S*)-12, which was prepared from the racemic chloridite (mixture of three diastereoisomers was obtained) a 7J(P(2),P(2')) of 36 Hz was observed.These observations provide strong evidence that seven-bond P,P coupling occurs in all three diastereoisomers of 12.The observed P,P coupling is both independent of the configuration of the chiral axis and the configuration of the asymmetric P-centers.This independence of P,P coupling upon the configuration on P implies also the .....
112. Sterically Congested Molecules: 2,2′-[(Biaryldiyl)bis(oxy)] bis[1,3,2-oxazaphospholidines]
Pastor, Stephen D.,Rodebaugh,Odorisio, Paul A.,Pugin, Benoit,Rihs, Grety,Tognic, Antonio
, p. 1175 - 1193 (2015/01/08)
The original suggestion that a through-space mechanism was operative in the seven-bond J(P,P) coupling constant of 30.3 Hz observed for 3,3′-bis(l,l-dimethylethyl)-2,2′-([3,3′,5,5′-tetrakis(l,l-dimethylethyl)-l,l′-biphenyl-2,2′-diyl]bis(oxy)}bis[l,3,2-oxazaphospholidine] (la) was investigated. In the solid-state CP-MAS 31P-NMR spectrum of la, two nonequivalent P-atoms were observed; sufticient resolution could not be obtained to determine whether P,P coupling was present. The preparation and spectral data of the N-methyl analogue lb and of the acyclic N-isopropyl analogue 6 (Scheme 1) provided evidence that a) the essentially exclusive formation (R,R,S)-la in the reaction of the disodium biphenyldiolate 3a with the phosphorochloridite 4a is the result of significant differences in the free energy of activation (ΔG ) for the formation of the various diastereoisomers due to the steric congestion within the molecule and that b) the magnitude of the observed P,P coupling is dependent upon the degree of conformational freedom within the molecule. In the 31P-NMR spectrum of the P-sulfide 7, which was prepared by the reaction of la with sulfur, 2s resonances were observed that strongly suggested that the lone electrons pair on P are involved in the mechanism for the transmission of coupling data. The chiral analogues (4S,5R)-12 and (4R,5S)-12 of la were prepared in a three-step reaction sequence starting from the corresponding enantiomerically pure norephredine 8 (Scheme 2). Both (4S,5R)-and (4R,5S)-12 were obtained as a diastereoisomer mixture that differ by the configuration of the axis of chirality, i.e., (R,R,R)-and (R,S,R)-12 were obtained. The major diastereoisomer was obtained upon recrystallization, and the atropisomers were observed to equilibrate in solution by monitoring the H-C(5) resonance in the 1H-NMR with time (δG° = 0.4 kcal/mol; Fig. 2). The process observed corresponds to the restricted rotation about the central single bond of the biphenyl system. The isolation of an atropisomer with only a single ortho substituent on each aryl ring is quite rare. In the 13C-NMR spectrum of both (R,R,R)-and (R,S,R)-12, C(5) is two-bond-coupled to the oxazaphospholidine P-atom (2J(C(5),P((2)) = 8.5 Hz) that is further virtually coupled to the P-atom of the other oxazaphospholidine ring (7J(P(2),P(2′)) = 30 Hz; 9J(C(5),P(2′)) = 0 Hz; δ(P(2)) = δ (P(2′)) = 136 ppm). In the 31P-NMR spectrum of (R,R,S)-12, which was prepared from the racemic chloridite (mixture of three diastereoisomers was obtained), a 7J(P(2),P(2′)) of 36 Hz was observed. These observations provide strong evidence that seven-bond P,P coupling occurs in all three diastereoisomers of 12. The observed P,P coupling is both independent of the configuration of the chiral axis and the configuration of the asymmetric P-centers. This independence of P,P coupling upon the configuration on P implies also the independence of the observed coupling upon the orientation of the lone-pair of electrons on P provided that the conformations of lhe diastereoisomers are similar in solution. The X-ray crystal structure of the complex formed from la and dichloro(cycloocta-l,5-diene)platinum(II) was obtained and the solid-state structure discussed. The major diastereoisomer of (4S,5R)-12 was used as a chiral ligand in asymmetric hydrosilylation and hydrogenation reactions (Scheme 3).
Synthesis of Phospholipids by Phosphoramidite Methodology
McGuigan, Christopher,Swords, Bernadette
, p. 783 - 787 (2007/10/02)
Novel phospholipids have been prepared by a rapid three-step procedure.The oxazaphosphacyclopentane (1) reacts with alcohols to yield cyclic phosphoramidites in high yield.These are oxidised to the corresponding phosphates with N2O4.The phosphates undergo P-N cleavage simply by treatment with water at ambient temperature, to yield phospholipids.Full spectroscopic and analytical data are presented and discussed.
Synthesis of some Nucleoside Cyclic Phosphoramidates and related compounds via Phosphoramidites
Jones, A. Stanley,McGuigan, Christopher,Walker, Richard T.
, p. 199 - 202 (2007/10/02)
Reaction of 2-chloro-3-methyl-1-oxa-3-aza-2-phosphacyclopentane with thymidine and with 2'-deoxy-5-fluorouridine gave their 3',5'-bis-O-(3-methyl-1-oxa-3-aza-2-phosphacyclopentan-2-yl) derivatives (5) and (6).Reaction of these nucleosides with 2-chloro-1,3-dimethyl-1,3-diaza-2-phosphacyclopentane gave 3',5'-bis-O-(1,3-dimethyl-1,3-diaza-2-phosphacyclopentan-2-yl) derivatives (7) and (8).The phosphoramidites, (7) and (8) were oxidised with dinitrogen tetroxide to the corresponding phosphoramidates (9) and (10).Attempts to oxidise (5) and (6) in a similar way resulted in opening of the phosphoramidate ring.Treatment of compounds (5)-(8) with sulphur gave the corresponding phosphorothioamidates (11)-(14).The hydrolysis of 3',5'-bis-O-(1,3-dimethyl-2-oxo-1,3-diaza-2-phosphacyclopentan-2-yl)thymidine (9) was studied using (31)P n.m.r. spectroscopy.At pH 7.0 and 25 deg C the half-life was 21 h.Both phosphorus heterocyclic rings opened at the same rate.The hydrolysis of the second ring proceeded at ca. three times the rate of hydrolysis of the first. 2'-Deoxy-5-fluoro-3',5'-bis-O-(1,3-dimethyl-2-oxo-1,3-diaza-2-phosphacyclopentan-2-yl)-uridine (10) did not inhibit isolated purified zhymidylate synthetase and was only a weak inhibitor of leukemia L1210 cell growth.
PREPARATION AND STRUCTURAL STUDIES OF A NUMBER OF HETEROCYCLIC PHOSPHORANES
Denney, Donald B.,Denney, Dorothy Z.,Liu, Lun-Tsu
, p. 71 - 84 (2007/10/02)
A series monocyclic five-membered ring containing trivalent phosphorous compound with oxygen, nitrogen and sulfur bonded to phosphorous, in various combinations has been allowed to react with trifluoroethyl and 1,1,1,3,3,3-hexafluoroisopropyl benzenesulfenates.In some cases, pentacoordinated phosphorous compounds resulted.These materials have been studied by various NMR techniques.The same trivalent phosphorous compounds were allowed to react with 3,4-(bistrifluoromethyl)1,2,dithiete.In some cases phosphoranes were formed and they were also studied by NMR.
