Studies of Organophosphorus Derivatives. Part I. Nuclear Magnetic Resonance Studies of the 2-Oxo-1,3,2-dioxaphosphorinane System

A complete nmr study (1H, 13C, 31P) of twelve 3-C-phosphonates, -phosphinates, and -phosphine oxide derivatives of 3-C-branched-chain pento- and hexo-furanoses is reported. For all compounds the configuration at C3 is determined and, for oxaphospholanes 9 to 12, the configuration at the asymmetric phosphorus atom. The 3T2 conformation of the furanose ring of acyclic derivatives 1 to 8 and the conformationally rigid cis-fused oxaphospholane-furanose bicyclic systems of 9 to 12 have been used to study the 3JPCCH vs. θP.H and 3JPCCC vs. θP.C relationships which are specific to this series of compounds. The use of the ν P=O ir stretching frequency, δ 31P chemical shift, and 1JP.C coupling constant values in structural analysis of C-phosphorus-bearing sugars is also reported and discussed.

Section: Spectroscopic Properties Of 312-phosphorus-bearingmentioning

confidence: 57%

Structural analysis of 3-C-phosphonates, -phosphinates, and -phosphine oxides of branched-chain sugars

Neeser¹,

Tronchet²,

Charollais³

1983

“…Of course glycosidic angle values closer to zero for 5'-GMP/L~"' at pH 1.2 (Table 4) range 'JpilJ. coupling constant in the complex when compared to the value of 1.2 Hz for the free ligand at the same pH (32).…”

Section: H{h}noe Valuesmentioning

confidence: 84%

“…Theoretical and experimental studies of 'JHkI and 'JPl, coupling constants through saturated bonds (32,33) have shown that they have maximum values for a planar W atom arrangement. These studies are applicable to 5'-GMP at low pH (pH < 2) as, when the guanine base is saturated, the bond order C,-N, is about one.…”

Section: H{h}noe Valuesmentioning

confidence: 99%

Conformation of purine mononucleotides by H{H} and P{H} nuclear Overhauser effects

Santos¹,

Xavier²,

Geraldes³

1983

The proton–proton and phosphorus–proton nuclear Overhauser effect (nOe) of guanosine 5′-monophosphate (5′-GMP) was measured in aqueous solution at different pH values and in the presence of excess LaIII at acid pH. These data and nOe data from the literature for other mononucleotides were used together with vicinal proton–proton coupling constants to investigate the conformations of mononucleotides in aqueous solution, especially their rotational state about the glycosidic bond. Comparison of observed and calculated enhancements using various conformational models for the glycosidic bond gave predominantly anti conformations for 5′-AMP and 5′-GMP and a mixture of syn and anti conformations for 2′-AMP, 2′-GMP, 3′-AMP, and 3′-GMP. Protonation of 5′-GMP at N-7 of the guanine base alters the amplitude of its torsion angle within the anti range. The agreement between the glycosidic nucleotide conformations defined by nOe and by the lanthanide probe method is good but not perfect. As complexation of 5′-GMP with LaIII through the phosphate group has only a small effect on the conformation of its exocyclic group, a comparison of the two methods is justified.

“…Similarly, a convenient 3~p O C H VS. OpH correlation can be easily deduced from many previous works (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), including studies of cyclic phosphates. This relationship has been shown to be susceptible to the coordination number of the phosphorus atom (27), ring-strain, and bond angle distortions (13b, 15,28).…”

mentioning

confidence: 99%

“…However, the l~p o C H VS. epH relationship proposed by Lee and Sarma (13a) (eq. [2]) has been used extensively and successfully for conformational assignment of various dioxaphosphorinane rings previously studied, including conformationally "free" six-membered rings (19,20), sixmembered phosphate rings fused cis to five-membered sugar rings (13b, 15), and similar trans-fused bicyclic systems (13a). The relevant function is:…”

mentioning

confidence: 99%

Synthesis and conformational studies of phosphate esters of 1,2-O-isopropylidene-α-D-ribo- and xylo- pentofuranoses

Neeser¹,

Tronchet²,

Charollais³

1983

. J . Chem. 61, 1387 (1983).The synthcsis and properties. particularly ' H , "P, and ' " nmr, of new phosphate estcrs of I ,2-0-isopropylidene-a-D-riboand xylo-furanoses arc described. For the cyclic phosphates the configuration at the asymmetric phosphorus atom is determined and for all derivatives the preferred conformation of the furanosc and dioxaphosphorinanc rings and the conformation around the phosphoester bonds are prcscnted. Thc dependency of 'Jr>occ coupling constants on factors other than dihcdral angles is reportcd and discussed.JEAN-RICHARD NEESER, JEAN M . J . TRONCHET ct ETIENNE J . CHAROLLAIS. Can. J . Chem. 61, 1387 (1983). Nous dCcrivons la synthhsc ct les proprietes spectroscopiques (en particulier de rmn ' H , "P ct "C) de nouveaux esters phosphoriques de 0-isopropylidkne-1 ,2-u-D-ribo-et xylo-furannoses. Pour les dCrivCs phosphatc cyclique, la configuration au nivcau de I'atome dc phosphore asyrnetriquc a CtC attribuCe, et pour tous nos composCs, la conformation prCfCrenticlle des cycles furannosique et dioxaphosphorinanne, ainsi que la conformation autour des liaisons phosphoester, sont dCterminCcs. Nous observons Cgalcment une variation des constantes dc couplage Ilr,occ en fonction d'autres facteurs quc les angles dikdres et discutons de la signification de tcls resultats.Considering the importance of pentose phosphates, either by themselves, as structural units of nucleotides, or in metabolic biochemical systems, we were prompted to study derivatives of two important naturally occurring pentoses, namely D-xylose and D-ribose. The observations made on these model compounds might prove useful in the understanding of the conformational properties of biologically important nucleotide derivatives.Syntheses of derivatives 1 to 12 were carried out from 1 ,2-0-isopropylidene-a-D-xylofuranose (A) or 1,2-0-isopropylidene-a-D-ribofuranose (B), as depicted in Fig. 1.Results and discussion 1. Itflared ntzd n~icle~zr magnetic resotzntzce spectroscopy.Conji:guratiot~al assigr~met~t of asjltntnetrical phosphorus atoms in compounds 1 to 4 As previously reported (6-9), the values of the P=O stretching frequency (around 1300 cm-') can be used successfully to assign the configuration of phosphorus atoms of a pair of asymmetrical phosphorus-containing epimeric dioxaphosphorinane rings. Such an assignment is dependent on the orientation of the P=O bond, resulting from the conformation of the heterocycles. For example, in compound 1: v P=O (equatorial) = 1295 cm-', and in compound 2: v P=O (axial) = 1285 cm-'.Tables 1-4 summarize the nrnr data for compounds 1 to 12. As previously reported (7-9), "P chemical shifts of derivatives 1 and 2 show a dependence similar to that of v P=O, as a function of the orientation of the phosphoryl bond: in compound 1, 6 "P = + 16.80 ( P = 0 equatorial) and in compound 2, 6 "P = + 14.10 (P=O axial). Configurational assignment of the phosphorus atom for 3 was deduced from a comparison of the 'H and "C nrnr spectra of 1 and 3. The phosphorus atom configuration for 4 was establish...