Synthesis and Evaluation of Chromogenic and Fluorogenic Analogs of Glycerol for Enzyme Assays

The branched glycerol analogs 1 and 2 were prepared. Mono‐ester derivatives of these triols undergo a chromogenic or fluorogenic reaction in the presence of NaIO₄. In contrast, both the diesters and the triols are themselves not chromogenic or fluorogenic. Diester derivatives of these triols can be used as probes for lipases. The tris‐phosphate derivative of 1 is a fluorogenic substrate for various phosphatases.     

The 1H NMR method for the determination of the absolute configuration of 1,2,3-prim,sec,sec-triols

The absolute configuration of 1,2,3-prim,sec,sec-triols can be assigned by comparison of the 1H NMR spectra of the tris-(R)- and the tris-(S)-MPA ester derivatives. An experimental demonstration of this correlation with 24 triols of known absolute configuration and a protocol using two parameters-Deltadelta(RS)(H3) and the difference between Deltadelta RS (H2) and Deltadelta RS (H3) = absolute value (Delta(Deltadelta RS))-for its application to the determination of the absolute configuration of other triols are presented.     

Oxydations par le carbonate d'argent sur celite—X : Oxydations de triols en serie androstane

The oxidation of androstane triols by silver carbonate on Celite is described. Androstane 3β, 5α, 6β-triol gives five compounds, and the observed selectivity depends on solvent polarity. The major product results from oxidation of the 6-hydroxyl group in benzene, and of the 3-hydroxyl group in chloroform. Androstane-3β, 5α, 6α-triol is oxidised selectivity at the 3 position. The results are interpreted according to the recently proposed mechanism, an hypothesis being proposed for the geometry of state of absorption of the triols.     

Dependence of viscoelastic spectrum width on the structure of model imperfect networks prepared by endlinking

Using the theory of branching processes, structural parameters such as the molecular weights of elastically active network chains (EANCs), including dangling chains, backbone EANCs and dangling chains of networks built up by the alternating polyaddition of a bi- and trifunctional monomer, are characterized. The theory is compared with viscoelastic data on polyurethane networks prepared from poly(oxypropylene)triols and diisocyanate at various initial ratios of functional groups; in the calculation, the distribution of functionalities of the triols used and the possible incompleteness of the reaction is taken into account. The comparison reveals that both the length of the backbone EANC and the length of dangling chains contribute to the total width of the retardation spectrum.     

Enantioselective total syntheses of kudtriol, 5-epi-kudtriol and their C-11 epimers

Two approaches for the enantioselective syntheses of naturally occurring kudtriol 2a and 5-epi-kudtriol 3a as well as their C-11 epimers are presented, both using the Sharpless asymmetric dihydroxylation as the key reaction. Through comparison of the spectral data of natural triols and synthetic samples, we could confirm the absolute configuration of the natural triols.     

Synthesis of Chiral Starburst Dendrimers from PHB-Derived Triols as Central Cores

Chiral triols 1 – 3 (‘tris(hydroxymethyl)methane’ derivatives), prepared from (R)-3-hydroxybutanoic acid and aldehydes, are used as center pieces of dendrimers. The triols may be employed as such or after attachment of spacers containing alkyl or aryl moieties (see 5 and 7 ). The branches combined with the original or elongated triols are those first reported by Fréchet ( 9 – 12 , benzyl ethers of 3,5-dihydroxybenzyl alcohol and bromide). In this way, 1st-, 2nd-, and 3rd-generation chiral dendrimers without ( 13 – 15 ), or with aliphatic ( 16 – 18 ) or aromatic ( 19 – 21 ) spacers are prepared. The molecular weights range from 447 to 2716 Dalton. Two of the chiral triols, i.e., 2 and 3 , are used as center pieces for chiral dendrimers containing 6 NH₂, or 6 and 12 NO₂ groups on the periphery ( 22 – 27 ), with 3,5-dinitrobenzoyl chloride as the branching unit. All compounds thus synthesized are of course monodisperse and are fully characterized. In some cases, the optical activity of the dendrimers indicates that conformationally chiral substructures might be present. The NH₂- and NO₂-substituted compounds avidly clathrate smaller molecules; they are sorbents exchanging host molecules through the gas phase.     

Zur Lokalisierung Funktioneller Gruppen mit Hilfe der Massenspektrometrie. XV—Massenspektren von androstanen mit Hydroxygruppen in den Positionen 3, 16 und 17

Compared with other isomeric androstane triols the mass spectra of those androstane triols with hydroxy groups in positions 3, 16 and 17 are characterized by intense molecular ions. Important fragment ions show the loss of C-15, C-16 and C-17 in the form of a fragment comprising 75 mass units. This ion shows facile loss of the hydroxy group in position 3 in the form of a water molecule producing a [M ? 93]⁺ ion. Further key ions are at m/e 60, 84 and 110. With the aid of three deuterated androstane trioles and high resolution it was shown that these ions contain parts of the D-ring system.     

Microbial hydroxylation of sclareol by Rhizopus stolonifer

Incubation of sclareol with Rhizopus stolonifer affords in high yield a mixture of triols with 18-hydroxy-sclareol as the main component.     

Hydrolyzable poly(ester-urethane) networks from L-lysine diisocyanate and D,L-lactide/ϵ-caprolactone homo- and copolyester triols

Bioabsorbable poly(ester-urethane) networks were synthesized from ethyl 2,6-diisocyanatohexanoate (L -lysine diisocyanate) (LDI) and a series of polyester triols. LDI was synthesized by refluxing L-lysine monohydrochloride with ethanol to form the ester, which was subsequently refluxed with 1,1,1,3,3,3-hexamethyldisilazane to yield a silazane-protected intermediate. This product was then phosgenated using triphosgene. Polyester triols were synthesized from D,L-lactide, ?-caprolactone, or comonomer mixtures thereof, using glycerol as initiator and stannous octoate as catalyst. Polyurethane networks were cured using [NCO]/[OH] = 1.05 and stannous octoate (0.05 wt %) for 24 h at room temperature and pressure and 24 h at 50°C and 0.1 mm Hg. LDI-based polyurethane networks were totally amorphous and possessed very low sol contents. Networks based on poly (D,L-lactide) triols were rigid (T_g ∽ 60°C) with ultimate tensile strengths of ～ 40–70 MPa, tensile moduli of ～ 1.2–2.0 GPa, and ultimate elongations of ～ 4–10%. Networks based on ?-caprolactone triols were low-modulus elastomers with tensile strengths and moduli of ～ 1–4 MPa and ～ 3–6 GPa, respectively, and ultimate elongations of ～ 50–300%. Networks based on copolymers displayed physical properties consistent with monomer composition and were tougher than the networks based on the homopolymers. Tensile strengths for the copolymers were ～ 3–25 MPa with ultimate elongations up to 600%. Hydrolytic degradation under simulated physiological conditions showed that D ,L -lactide homopolymer networks were the most resistant to degradation, undergoing virtually no change in mass or physical properties for 60 days. ?-Caprolactone-based networks were resistant to degradation for 40 days, and high-lactide copolymer-based networks suffered substantial losses in physical properties after only 3 days. © 1994 John Wiley & Sons, Inc.     

Conformations of isomeric Z and E enyne triols and dihydroxyaldehydes

PMR has been applied to enyne triol conformations. The conformation differences between the Z and E enyne triols are due to differences in intramolecular interactions. The Z and E isomers of primary-ditertiary enyne triols have been oxidized to obtain the corresponding dihydroxyaldehydes. The chemical shifts and spin-spin interaction constants SSIC for the protons show that the conjugated system does not remain coplanar in the dihydroxyaldehyde E isomers.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 6, pp. 681–688, November–December, 1990.     

Melynes,polyacetylene constituents from a vanuatu marine sponge

The structures of three long chain polyeneyne triols, melynes A, B, C are established from degradation reactions, from NMR data and from extensive HREIMS data.     

Unexpected tosyl deprotection during osmium catalysed dihydroxylation

Depending on the double bond position, tosyl deprotection was observed during olefin dihydroxylation using osmium tetroxide, leading to triols.     

Transacetalisation de triols a partir du dimethoxymethane. Selectivite et applications synthetiques

The LiBr assisted/acid catalyzed transacetalation of triols from DMM affords a highly selective method for the synthesis of hydroxy compounds bearing a dioxane ring. These compounds might further conveniently be alkylated by phase transfer catalyzis.     

Epimerization by Non‐classical Acetalization—A New Three Component Reaction for Carbohydrates and Inositols

This mini‐review summarizes the knowledge about the scope and pathway of a novel non‐conventional tandem procedure of acetalization which allows a simultaneous epimerization of cyclic polyols with three or four contiguous hydroxyl groups. Such triols and tetrols, e.g., pyranosides or inositols, form acetols on heating with highly active aldehydes or ketones in the presence of a carbodiimide, provided that their OH‐groups show a cis/trans or cis/trans/trans sequence. The inversion of one chiral center (triols) and of one or two chiral centers (tetrols) was achieved. The stepwise removing of the protecting groups is reported.     

Tandem enzyme-catalysed oxidations of alkyl phenyl sulfides and alkyl benzenes: enantiocomplementary routes to chiral phenols

Dioxygenase-catalysed trioxygenation of alkyl phenyl sulfides and alkyl benzenes yields enantiopure cis-dihydrodiol sulfoxides and triols respectively; naphthalene cis-dihydrodiol dehydrogenase-catalysed aromatisation of these diastereoisomers gives enantiopure catechols of either configuration.     

Enzymatic synthesis of a ring-contracted analogue of 5-enolpyruvylshikimate-3-phosphate

[reaction: see text] Three ring-contracted mimics of shikimate-3-phosphate, formed from the triols by shikimate kinase, were evaluated as substrates of the next enzyme in the pathway, EPSP synthase. The cyclopentylidene analogue (+)-2P was converted enzymatically to the enolpyruvyl derivative, thus demonstrating the second step of an artificial biosynthetic sequence.     

Toward Creation of a Universal NMR Database for Stereochemical Assignment: The Case of 1,3,5‐Trisubstituted Acyclic Systems

Using the diastereoisomeric triols 1a – d (Fig. 1) and examples summarized in Fig. 2, the central C‐atom of acyclic 1,3,5‐triols is demonstrated to exhibit a distinctive chemical shift that is dependent on the 1,3‐ and 3,5‐relative configuration, but is independent of the functionalities present outside of this structural motif. These NMR characteristics are then used to predict the relative configuration of several natural products (Fig. 7). In addition, an example is given to show the possibility of assembling an NMR database for a larger array of functional groups from NMR databases of smaller arrays of functional groups.     

New synthesis of monomethyl ethers of triols — Extraction agents for boric acid

Conclusions A new method for the synthesis of monomethyl ethers of triols starting from acetylenic ketones has been developed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 621–623, March, 1987.     

Characterization of oxygenated derivatives of isoprene related to 2-methyltetrols in Amazonian aerosols using trimethylsilylation and gas chromatography/ion trap mass spectrometry

In the present study, we have tentatively identified the structures of three oxygenated derivatives of isoprene in Amazonian rain forest aerosols as the C(5) alkene triols, 2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene. The formation of these oxygenated derivatives of isoprene can be explained by acid-catalyzed ring opening of epoxydiol derivatives of isoprene, namely, 1,2-epoxy-2-methyl-3,4-dihydroxybutane and 1,2-dihydroxy-2-methyl-3,4-epoxybutane. The structural proposals of the C(5) alkene triols were based on chemical derivatization reactions and detailed interpretation of electron and chemical ionization mass spectral data, including data obtained from first-order mass spectra, deuterium labeling of the trimethylsilyl methyl groups, and MS(2) ion trap experiments. The characterization of 2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene in forest aerosols is important from an atmospheric chemistry viewpoint in that these compounds hint at the formation of intermediate isomeric epoxydiol derivatives of isoprene and as such provide mechanistic insights into the formation of the previously reported 2-methyltetrols through photooxidation of isoprene.     

Tris-phosphorylated esters of symmetrical and unsymmetrical triols

By reaction of a series of triols and monosaccharides with 5,5-dimethyl-2-chloro-1,3,2-dioxaphosphorinane their tris-phosphorylated derivatives were synthesized, and the simplest chemical transformations of the latter were studied. Structures of the obtained P(V) derivatives were confirmed by ¹H, ¹³C and ³¹P NMR spectroscopy and by the MALDI TOF mass spectrometry and X-ray structural analysis.