Synthesis of 2, 5-disubstiututed tetrahedrofurans from organozinc halides and lactones

2,5-Disubstituted tetrahydrofurans were obtained from lactones and organozinc halides in moderate to high yield in the presence of Lewis acids.     

Sesquiterpene lactones ofPyrethrum pyrethroides. II. Pyrethroidin

A new sesquiterpene lactone, pyrethroidin, and a known one — 8-deoxycumambrin B — have been isolated from the epigeal part of the plantPyrethrum pyrethroides. The structure of 4,10-dihydroxy-1,5,7(H),6(H)-guaia-2,11(13)-dien-6,12-olide has been suggested for pyrethroidin.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 199–201, March–April, 1985.     

Aminocyclopentanols as sugar mimics. Synthesis from unsaturated bicyclic lactones by Overman rearrangement

Bicyclic cyclopentane lactones, prepared from bromodeoxyaldonolactones, were transformed into aminocyclopentanols with an Overman rearrangement as the key step. Two of the compounds prepared, 7 and 19, were found to be good inhibitors of jack bean alpha-mannosidase and beta-D-N-acetylglucosaminidase, respectively.     

Synthesis of 2,5-disubstituted tetrahydrofurans from organozinc halides and lactones

<正>2,5-Disubstituted tetrahydrofurans were obtained from lactones and organozinc halides in moderate to high yield in the presence of Lewis acids.     

Anionic polymerization of lactones initiated by alkali graphitides. II. Changes in the KC24 structure during polymerization of lactones

The structural changes in the potassium graphitide KC₂₄ in its interaction with ?-caprolactone, γ-butyrolactone and pivalolactone are examined by profilometric measurement and electron scanning microscopy. The interaction of KC₂₄ with a nonpolymerizable lactone-γ-butyrolactone proceeds without delamination of the graphitide. The polymerization of ?-caprolactone and pivalactone in the interlayer spaces of KC₂₄ leads to destruction of the initiators structure. An increase in the temperature and monomer concentration enhances the delamination of the graphitide.     

Organocuprate reactions of enone lactones. II. Regiochemical effect on reductive cleavage.

The course of organocuprate conjugate addition and reduction in cyclohexenones made conformationally rigid by attachment of a 1,3-lactone is shown to depend on the regiochemistry of such enones.     

5-Arylideneaminouracils: II. Synthesis of sodium and ammonium salts

In continuation of studies on the design of new 5-arylideneaminouracil derivatives possessing antimicrobial and antiviral properties, the corresponding ammonium and sodium salts were synthesized. The antimicrobial activity of water-soluble salts of substituted aminouracils in vitro was shown to be several times higher than that of parent neutral compounds.

     

Synthesis of lactones with a chlorodifluoromethyl group

Synthetic routes to lactones with a chlorodifluoromethyl group via S_N2′, oxidation and lactonization reactions, were described.     

Sesquiterpene lactones from Centaurea rhizantha C.A. Meyer

Two new sesquiterpene lactones, rhizantholide A (1) and rhizantholide B (2), together with five known compounds (3-7) have been isolated from the aerial parts of Centaurea rhizantha (Asteraceae). Sesquiterpene lactones belong to guaianolide class, and rhizantholide B is a rare guaianolide characterized by a free primary alcoholic function at C-10 along with a 3β,10β-epoxy function. Their structures have been established on the basis of 1D and 2D NMR experiments, as well as HR-ESIMS. The antimicrobial activity of compounds 1-7 has been evaluated against Gram-positive and Gram-negative strains. Only deacylcynaropicrin 8-O-[3′-hydroxy-2′-methylpropionate] (5) showed moderate antibacterial activity against Staphylococcus aureus with a MIC/MBC value of 500 μg/mL. All isolated compounds have been also evaluated for their cytotoxic activities against cancer cells. Among them, compound 5 showed the highest cytotoxic activity with IC₅₀ values in the range 5.02–16.76 μg/mL.     

Synthesis of organosilicon lactones based on vinylacetic acid

6-Membered ring organosilicon lactones, with various substituants on the silicon atom, are prepared.     

Stereochemistry of terpene derivatives. Part 5: Synthesis of chiral lactones fused to a carane system—insect feeding deterrents

Chiral iodo- 9, bromo- 10 and hydroxylactones 12 condensed with the carane system were obtained. In each case, the synthetic pathway led to an enantiomerically pure diastereoisomer to generate two stereogenic centers. Iodo- 9 and bromolactone 10 possess a γ-lactone group while the hydroxylactone 12 possesses a δ-lactone moiety situated trans to the gem-dimethylcyclopropyl ring. The structures of the products were confirmed by X-ray crystallography. These lactones were tested for antifeedant activity against storage pest insects.     

Synthesis and some transformations of functionally substituted lactones

Reactions of functionally substituted unsaturated five- and six-membered cyanolactones with α- and β-hydroxy ketones in the presence of sulfuric acid gave substituted 2-oxofuran- and 2-oxopyran-3-carboxamides. Hydrolysis of some keto amides thus obtained afforded the corresponding carboxylic acids, and reactions with hydrazines and semicarbazides led to hydrazones and semicarbazones at the side-chain oxo group.     

Synthesis of macrocyclic lactones with methoxysulfonyl side chain

Two representative macrocyclic lactones with methoxysulfonyl side chain（5a and 5b）were synthesized employing Michael addition with acrolein and ring enlargement as the key steps,starting from potassium,α-oxocycloaikylsulfonates（1）in total yields of 45 and 57%,respectively.