THF Derivatives Research Articles

Metallated 2‐Alkenyl Sulfoximines in Asymmetric Synthesis: Regio‐ and Stereoselective Synthesis of Highly Substituted Tetrahydrofurans

AbstractStarting from the enantiopure 2‐alkenyl sulfoximines 4/5 and epi‐4/5, a one‐pot procedure has been developed for the synthesis of tri‐ and tetrasubstituted tetrahydrofuran derivatives with excellent control of all relevant aspects of their structural description. The cyclization of the intermediate γ‐hydroxyvinyl sulfoximines is strictly regioselective due to the electronic properties of the double bond involved. The absolute configuration at C‐2 can be selected at will by a proper choice of the corresponding lactaldehydes 14 or ent‐14 respectively. The absolute configuration at the 3‐ and 4‐positions of the THF derivatives is under control of the sulfoximine moiety during aldehyde uptake, whereas their relative configuration is fixed due to the 1k relative topicity of attack of the reactands involved in their generation. The configuration at position 5 is determined mainly by the release of 1,3‐allylic strain and is therefore the only stereogenic centre under substrate control. This becomes obvious in two cases (17a and 18a) where stereocontrol at this position is diminished. Here, the absence of a 3‐methyl group as a control element reduces the energetic difference between the Re‐ and the Si‐side attack.

ChemInform Abstract: Acidity of Dibasic Carbon Acids. Part 3. Ion Solvation State of Monometallic Salts of 9,10‐Dihydroanthracene and Its Derivatives in THF

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Bis-esters from maleic anhydrides under neutral conditions: Protection of the anhydride of the natural product cornexistin

Trimethylsilyldiazomethane converts maleic anhydride derivatives in alcoholic THF to bisesters. The highly acid and base sensitive natural product cornexistin was converted to its bis-methyl ester in 70–75% yield and to the mixed benzyl/methyl ester in 61% yield. The mixed ester can be converted back to cornexistin via transfer hydrogenation.

Acidity of dibasic carbon acids. Part 3. Ion salvation state of monometallic salts of 9,10-dihydroanthracene and its derivatives in THF

The ion solvation state of monometallic salts of 9,10-dihydroanthracene (DHA) and its 9,10-disubstituted derivatives in THF has studied by UV–VIS and 1H and 13C NMR spectroscopy. At room temperature, lithium 9-phenyl-9,10-dihydroanthracen-9-ide, lithium 9,10-dimethyl-9, 10dihydroanthracenide and lithium 9,10-diphenyl-9,10-dihydroanthracemde exist as solvent separated ion pairs (SSIP). Lithium 9,10-dihydroanthracene, lithium 9-methyl-9,10-dihydroanthracen-10-ide and sodium, potassium and rubidium 9-phenyl-9,10-dihydroanthracen-9-ides, 9,10-dimethyl-9, 10dihydroanthracenides and 9,10-diphenyl-9,10-dihydroanthracenides exist as a mixture of SSIP and contact ion pairs (CIP). Sodium, potassium, rubidium and caesium 9,10-dihydroanthracenides, 9-methyl-9,10-dihydroanthracen-10-ides and 9-cyano-9,10-dihydroanthracenides exist as CIP in solution. The stabilizing effect of the methyl and phenyl substituents is more significant for SSIP than for CIP. The thermodynamics for SSIP to CIP conversion is determined for the sodium salts of DHA and its derivatives. ΔS° is 27 ± 2 cal mol–1 K–1ΔH° increases with substituent size and charge dispersion. A model for the transition of CIP of alkali-metal salts of DHA and its derivatives into SSIP is suggested. The model takes into account the geometry and charge distribution in anions.

Acidity of dibasic carbon acids. Part 4. Structure and ion solvation state of dimetallic salts of 9,10-dihydroanthracene and its derivatives in tetrahydrofuran

The ion solvation state of dimetallic salts (M = Li–Cs) of 9,10-dihydroanthracene (DHA) and its derivatives in THF was studied by UV–VIS and NMR spectroscopies. The cations are situated on the opposite sides of the dianion plane in the dimetallic salts. Cation–dianion interaction stabilized the negative charge of the carbanion. The mechanism of dianion charge stabilization is affected by a phenyl substituent.

ChemInform Abstract: Synthesis of Tetrahydrofuran and Tetrahydropyran Derivatives from Terpenes. Part 4. Conversion of cis‐1,3‐bis(2‐Hydroxypropyl)‐2,2‐ dimethylcyclopropane to THF and THP Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of (.eta.5-C5Me5)Ru(.eta.6-tryptamine)(CF3SO3) Complexes. Chemospecific .eta.6 Coordination of the (.eta.5-C5Me5)Ru+ Moiety

A series of Cp*Ru(eta6-N(b)-acyltryptamine)OTf and Cp*Ru(eta6-N(b)-CBZ-tryptamine)OTf complexes have been prepared from the reaction of Cp*Ru(CH3CN)3OTf (1) with the corresponding N(b)-acyl-tryptamine and N(b)-CBZ-tryptamine derivatives in THF at ambient reaction conditions under an argon atmosphere. The complexes are air stable and were obtained in high yields (>90%). Cp*Ru(eta6-N(b)-BOC-tryptamine]OTf (10) and Cp*Ru(eta6-N(b)-CBZ-tryptamine)OTf(16) were readily converted into Cp*Ru(eta6-tryptamine)OTf (3) in good yields (61% and 87%, respectively). The kinetic eta6 coordination of the electrophilic Cp*Ru+ moiety was found to be chemospecific for the electron-rich indole nucleus. No competing eta6 coordination was observed at the arene unit of a variety of substituted N(b)-CBZ-tryptamine derivatives.

13C NMR detection of folate-mediated serine and glycine synthesis in vivo in Saccharomyces cerevisiae.

Saccharomyces cerevisiae has both cytoplasmic and mitochondrial C1-tetrahydrofolate (THF) synthases. These trifunctional isozymes are central to single-carbon metabolism and are responsible for interconversion of the THF derivatives in the respective compartments. In the present work, we have used 13C NMR to study folate-mediated single-carbon metabolism in these two compartments, using glycine and serine synthesis as metabolic endpoints. The availability of yeast strains carrying deletions of cytoplasmic and/or mitochondrial C1-THF synthase allows a dissection of the role each compartment plays in this metabolism. When yeast are incubated with [13C]formate, 13C NMR spectra establish that production of [3-13C]serine is dependent on C1-THF synthase and occurs primarily in the cytosol. However, in a strain lacking cytoplasmic C1-THF synthase but possessing the mitochondrial isozyme, [13C]formate can be metabolized to [2-13C]glycine and [3-13C]serine. This provides in vivo evidence for the mitochondrial assimilation of formate, activation and conversion to [13C]CH2-THF via mitochondrial C1-THF synthase, and subsequent glycine synthesis via reversal of the glycine cleavage system. Additional supporting evidence of reversibility of GCV in vivo is the production of [2-13C]glycine and [2,3-13C]serine in yeast strains grown with [3-13C]serine. This metabolism is independent of C1-THF synthase since these products were observed in strains lacking both the cytoplasmic and mitochondrial isozymes. These results suggest that when formate is the one-carbon donor, assimilation is primarily cytoplasmic, whereas when serine serves as one-carbon donor, considerable metabolism occurs via mitochondrial pathways.

ChemInform Abstract: Synthesis of Tetrahydrofuran and ‐pyran Derivatives from Terpenes. Part 3. Conversion of cis‐2‐(3‐(2‐Hydroxypropyl)‐2,2‐dimethylcyclopropyl)ethanol to THF and THP Derivatives.

AbstractAcid‐catalyzed rearrangement of the diol (I), obtained by ozonolysis of (+)‐car‐3‐ene, yields the THF and THP derivatives (II)‐(V), which are separated and identified (1H, 13C NMR) following oxidation to the corresponding ketones and aldehydes.

Studies on the Synthesis of Tetrahydrofuran and ‐pyran Derivatives from Terpenes, III. Conversion of cis‐2‐[3‐(2‐Hydroxypropyl)‐2,2‐dimethylcyclopropyl]ethanol to THF and THP Derivatives

AbstractSulfuric acid‐catalyzed reaction of cis‐diol 1 leads to a mixture of four heterocyclic alcohols 2–5, which after oxidation yield a mixture of carbonyl compounds 6–9. These compounds were separated and their structures were determined on the basis of spectral data and GC analysis. It was found that THF deriatives (2 and 4) are the main rearrangement products of diol 1, and their high percent ratio in the mixture is discussed as a result of thermodymamic equilibrium between THF (2, 4) and THP (3, 5) derivatives.

ChemInform Abstract: Metal Donor → Metal Acceptor Complexes: Fe(CO)42‐, HFe(CO)4‐, and trans‐ HFe(CO)3P(OMe)3‐ as Anionic Ligands to M(CO)50 , M: Cr, W.

AbstractThe mixed metal binuclear anions are prepared as PPN salts (III) by direct reaction of PPN+ salts of [H Fe(CO)3L′]" (I) with labile THF derivatives (II) of group 6 metal carbonyls photochemically generated.

ChemInform Abstract: Synthesis of Chiral 18‐Crown‐6 Derivatives and Dibenzocrown Ethers Incorporating trans‐Tetrahydrofuran‐2,5‐diylbis(methylene) Units of Known Absolute Configuration.

AbstractThe optically active THF derivatives (Ib)‐(Id) [prepared from (Ia)] are converted to the crown ethers (IIa), (IIc) and (Vb).