Tetrahydropyran Derivatives Research Articles

An alternative procedure for the stereoselective formation of tetrahydropyran derivatives via 6-endo ring closure

Treatment of the acetylenic epoxides 1 having electron-donating groups at the acetylenic terminus with a catalytic amount of BF 3⊎OEt 2 afforded 6-endo products with inversion of stereochemistry at the propynyl position in a highly stereoselective manner, whereas the acetylenic epoxides 1 possessing electron-withdrawing substitutents at the acetylenic terminus provided under similar acidic condition the corresponding tetrahydrofuran derivatives in a highly selective way.

Regioselective and stereospecific formation of 2-ethynyl-3-hydroxytetrahydropyran derivatives via 6-endo ring closure

Efficient access to tetrahydropyran derivatives via highly regio- and stereoselective 6-endo tet mode ring opening of an epoxide by an internal hydroxy group has been developed. Cobalt complexes, derived from trans-4,5-epoxy-6-heptyn-1-ols and dicobalt octacarbonyl were treated with a catalytic amount of BF 3·OEt 2 in CH 2Cl 2 at −78°C to afford cis-2-ethynyl-3-hydroxytetrahydropyran derivatives in a highly regio- and stereoselective manner. Similar treatment of cis-4,5-epoxides provided the corresponding trans-tetrahydropyrans selectively.

ChemInform Abstract: Selective Cleavage of Asymmetric Acetals to Hemiacetal Acetates. Ring Opening of Chlorinated 2‐Alkoxytetrahydrofuran and ‐tetrahydropyran Derivatives.

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The Intramolecular Silyl-Modified Sakurai (ISMS) reaction. Stereoselective preparation of tri-and tetra-substituted tetrahydropyrans.

The ISMS condensation of allylsilane 4 does not follow the expected pathway but rather leads to an efficient synthesis of trisubstituted and tetrasubstituted tetrahydropyran derivatives.

Patent Evaluation: Novel cyclohexane and tetrahydropyran derivatives as antifungal agents

Patent Evaluation: Novel cyclohexane and tetrahydropyran derivatives as antifungal agents

Synthesis and biological evaluation of novel chiral non-racemic diaminoplatinum analogs based on a tetrahydropyran motif

Mono and dihydroxy diamino tetrahydropyran derivatives, readily available from L-arabinose, were prepared and converted into the corresponding diamino cis-platinum analogs. The presence of hydroxy groups imparts water solubility and enhanced antitumor activity.

Selective Cleavage of Asymmetric Acetals to Hemiacetal Acetates. Ring Opening of Chlorinated 2‐Alkoxytetrahydrofuran and ‐Tetrahydropyran Derivatives

AbstractAsymmetric acetals of α‐chloro and α,α‐dichloroaldehydes in acetic anhydride containing sulfuric acid afforded hemiacetal acetates at convenient rates at room temperature resp. at 127°C. The main product involved cleavage to the better stabilized α‐alkoxycarbenium ion intermediate, with a typical ratio 87:13 for ethyl:methyl and 94:6 for propyl:2‐chloroethyl. For 2‐alkoxytetrahydrofuran and ‐tetrahydropyran substrates (alkyl = methyl, ethyl, 2‐chloroethyl) ring cleavage was predominant (89‐98%).The kinetics were affected by several factors: the concentration of strong acid and of acetic anhydride (ionizing power of the medium), the ring size, nature and conformation of the 2‐alkoxygroup and by a minor side‐reaction that consumes acid by alkylation of its anion (OMe > OEt; eq. OMe > ax. OMe).

Conformational preferences for hydroxyl groups in substituted tetrahydropyrans

Quantum mechanical (ab initio and semiempirical) and force field calculations are reported for representative torsion potentials in several tetrahydropyran derivatives. The overall agreement between the various methods is quite good except that the AMBER torsion profiles are sensitive to the choice of atomic point charges. Using electrostatic potential (ESP) derived atomic point charges determined with the STO-3G basis set we find that AMBER is able to match the best quantum mechanical results quite well. However, when the point charges are derived using the 6-31G* basis set we find that scaling the intramolecular electrostatic nonbond interactions is necessary. AM1 does not work very well for these compounds when compared to the ab initio methods and, therefore, should only be used in cases when ab initio calculations would be prohibitive. Based upon our results we feel that any force field that makes use of 6-31G* ESP derived atomic point charges will need to scale intramolecular interactions. Implications of scaling intramolecular interactions to the development of force fields based on 6-31G* ESP derived atomic point charges are discussed. © 1992 by John Wiley & Sons, Inc.

Allene Epoxidation. Highly functionalized tetrahydrofurans and tetrahydropyrans from the oxidative cyclization of allenic alcohols.

The dimethyldioxirane oxidation of various allenic alcohols yields highly functionalized tetrahydrofuran and tetrahydropyran derivatives via intramolecular nucleophilic addition of the hydroxy group to an intermediate allene diepoxide.

A new series of natural antifungals that inhibit P450 lanosterol C-14 demethylase. I. Taxonomy, fermentation, isolation and structural elucidation.

A new series of antifungal antibiotics, Ro 09-1470 and its 6 congeners were isolated from the fermentation broth of Penicillium sp. NR6564. Their structures were determined as tetrahydropyran derivatives with an alkenyl side chain on the basis of their spectroscopic and physico-chemical properties. Among these compounds, Ro 09-1470 and Ro 09-1545 possessing a glycyl N-substituted glycyl ester residue had high antifungal activity. Ro 09-1469, one of the congeners, was found in the fermentation broth of several strains of Aspergillus sclerotiorum Huber.

Conversion of the Synthetic Precursor for Ipecac and Corynanthe Alkaloids into Synthetic Intermediates of Quinine Alkaloids and (±)-Dihydroantirhine

The epimeric mixture of the trans-substituted tetrahydropyran derivatives (1) was transformed to the cis-substituted lactone (6), which was converted into the piperidine (3), the synthetic intermediate of dihydrocinchonine (5a) and dihydrocinchonidine (5b), and the synthetic precursor (11) of (±)-dihydroantirhine (4)

Rearrangements of 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans reactions of paulownin and wodeshiol with triethylsilane and BF 3-etherate

Paulownin on treatment with triethylsilane and BF 3-etherate reacts in a similar manner to gmelinol, giving an aryltetralin as the product. In contrast, wodeshiol under the same conditions rearranges to two isomeric tetrahydropyran derivatives, the structures of which have been deduced on the basis of their 1H and 13C n.m.r. spectra, including NOE and spin decoupling experiments.

Synthesis of trifluoromethylated tetrahydropyrans from ene reaction products of trifluoromethyl ketones: synthesis of fluorine analogues of sesquiterpenes

Ene reaction of trifluoromethyl ketones were investigated extensively, 1) and the ene reaction products were transformed to many types of trifluoromethyl compounds. 2) Among these research, the ene reaction products of trifluoromethyl ketones were converted to α-trifluoromethylated tetrahydrofurans. In this study, derivatization of the ene reaction products to α-trifluoromethylated tetrahydropyrans were accomplished. Therefore, treatment of esters of 3,4-unsaturated alcohols with trifluoromethyl ketones gave α-(trifluoromethyl)homoallyl alcohol derivatives, which were hydrolyzed to 2,3-unsaturated 1,5-diol compounds. These were oxidized to δ-ketoalcohols. Hydrogenation of these alcohols, followed by treatment with Grignard reagents, gave trifluoromethylated 1,5-diols, which were dehydrated and cyclized to α- trifluoromethylated tetrahydropyran derivatives, some of which are fluorine analogues of curcumene ether, a sesquiterpene.

ChemInform Abstract: Stereoselective Syntheses of S‐Phenyl Tetrahydrofuran‐2‐thiocarboxylate and Tetrahydropyran‐2‐thiocarboxylate Derivatives Using (Phenylthio)nitromethane.

AbstractThe aldehydes (I) are coupled with the nitromethane (II) and subsequently dehydrated to yield the nitromethylene derivatives (III).

Addition of benzotriazole to vinyl ethers. Chemistry of the adducts

Benzotriazole adds readily to ethyl vinyl ether, to 2,3-dihydrofuran, and to 3,4-dihydro-2H-pyran to form the respective α-benzotriazolyl ethers. Reactions of benzotriazole with α-methoxy derivatives of tetrahydrofuran and tetrahydropyran give similar products by substitution of benzotriazolyl for the methoxy groups. The corresponding adducts of benzotriazole and vinyl acetates are unstable and eliminate acetate anion to form geminal bis(benzotriazolyl)alkanes. The products show benzotriazol-1-yl to -2-yl isomerization. α-Benzotriazolyl derivatives of tetrahydrofuran and tetrahydropyran react with phenyl- and alkynyl-magnesium reagents to give the respective α-phenyl or α-alkynyl cycloethers. Alkylmagnesium halides by contrast attack the benzotriazolyl N-3 atom of these adducts and open the tetrahydropyranyl ring with formation of an N,N′-disubstituted o-phenylenediamine. 1H and 13C NMR spectra of the products are discussed.

Stereocontrolled Synthesis of C18-C24 Fragments of Isolasalocid A and Lasalocid A. An application of the Acid Assisted Synthesis of Functionalized Tetrahydrofurans and Tetrahydropyrans

The allyl alcohol (9) derived from D-glucose was easily cyclized by acid treatment and then converted to the C 18 -C 24 fragment (13) of isolasalocid A (5). Similarly, the allyl alcohol (15) derived from ethyl L-lactate was converted to the C 18 -C 24 fragment (20) of lasalocid A (6) via the tetrahydropyran derivative (16), which was kinetically formed by a chelation-controlled reaction

Stereoselective syntheses of S-phenyl tetrahydrofuran-2-thiocarboxylate and tetrahydropyran-2-thiocarboxylate derivatives using (phenylthio)nitromethane

(Phenylthio)-nitromethane is a useful reagent for the synthesis of tetrahydrofuran and tetrahydropyran derivatives from γ- and δ-hydroxy aldehydes

Reactions of N-substituted allylacetic acid amides with selenium and tellurium tetrahalides

The addition of selenium tetrabromide to the olefinic bond of N-substituted allylacetic acid amides (reagent molar ratio 2∶1) proceeds counter to Markownikoff's rule with the formation of tetrahydrofuran derivatives. The addition of tellurium tetrahalides under the same conditions (reagent molar ratio 1∶1) proceeds in accordance with Markownikoff's rule with the formation of tetrahydropyran derivatives.

Heterocyclisations des hydroxy-6 methoxy-2 hexene-2 et heptene-2 oates de methyle.

Tetrahydropyran derivatives 14 – 17 and 22 – 25 are formed in good yields by cyclisation of methyl-6-hydroxy-2-hexenoate 6 or 2-heptenoate 7 mediated by various electrophilic reagents (mCPBA, benzeneselenyl chloride, N-bromosuccinimide, iodine). Cyclisations of Z and E isomers are stereospecific. The diastereoselectivity of cyclisation of the secondary alcohol 7 varies with the nature of the electrophilic reagent.

ChemInform Abstract: Stereoselective Reduction of Bicyclic Acetals. A Method for Reductive Generation of Heterocyclic Ring Systems.

AbstractThe reduction of bicyclic acetals such as (I) or (IV), yielding tetrahydropyran derivatives such as (II) or (V) and (VI) is studied.