Bismuth(III) Chloride (BiCl3); An Efficient Catalyst for Mild, Regio- and Stereoselective Cleavage of Epoxides with Alcohols, Acetic Acid and Water

Aliphatic carboxylic acid as a hydrogen-bond donor for converting CO2 and epoxide into cyclic carbonate under mild conditions

The catalytic systems of aliphatic carboxylic acids/quaternary ammonium halides could efficiently convert the coupling of CO₂ and epoxide into cyclic carbonates under mild conditions (80 °C and 4 bar CO₂).

A Convenient and Chemoselective Acetylation and Formylation of Alcohols and Phenols Using Acetic Acid and Ethyl Formate in the Presence of Bi(III) Salts

A variety of alcohols are acetylated and formylated efficiently with acetic acid and ethyl formate in the presence of catalytic amounts of Bi(III) salts such as BiCl3, Bi(TFA)3 and Bi(OTf)3. BiCl3 and Bi(OTf)3 are also effective catalysts for acetylation of phenols. All of these catalysts are ineffective in formylation of phenols. Selective acetylation and formylation of alcohols in the presence of phenols is an additional advantage of this procedure.

Total synthesis of pactamycin and pactamycate: a detailed account

This article describes synthetic studies that culminated in the first total synthesis of pactamycin and pactamycate and, in parallel, the two known congeners, de-6-MSA-pactamycin and de-6-MSA-pactamycate, lacking the 6-methylsalicylyl moiety. Starting with L-threonine as a chiron, a series of stereocontrolled condensations led to a key cyclopentenone harboring a spirocyclic oxazoline. A series of systematic functionalizations led initially to the incorrect cyclopentanone epoxide, which was "inverted" under solvolytic conditions. Installation of the remaining groups and manipulation of the oxazoline eventually led to pactamycin, pactamycate, and their desalicylyl analogues.

Bioactive Semisynthetic Derivatives of (S)-(+)-Curcuphenol

New semisynthetic sesquiterpene derivatives (3–7, 10), together with two known ones (8–9) were prepared from ( S)-(+)-curcuphenol (1), isolated from the Caribbean sponge Didiscus oxeata. The natural sesquiterpenes 1 and ( S)-(+)-curcudiol (2), as well as semisynthetic derivatives 3–10, were evaluated against the herbivorous insect species Spodoptera littoralis, Leptinotarsa decemlineata and Rhopalosiphum padi. All compounds had an antifeedant effect on L. decemlineata. With R. padi, a structure-dependent antifeedant response was observed, with 1 being the most active, followed by 4 and 5. Furthermore, compounds 1, 4, 5, 7, 8 and 10 reduced S. littoralis larval weight, with 10 also reducing ingestion by S. littoralis larvae. Of the derivatives studied here, none showed stronger effects (either antifeedant or postingestive) than the parent compound 1. It can, therefore, be concluded that the structure of the side chain and the presence of the phenol ring of curcuphenol are important structural requirements for its insect antifeedant and growth regulation effects.

Hot water-promoted ring-opening of epoxides and aziridines by water and other nucleopliles

Effective hydrolysis of epoxides and aziridines was conducted by heating them in water at 60 or 100 degrees C. Other types of nucleophile such as amines, sodium azide, and thiophenol could also efficiently open epoxides and aziridines in hot water. It was proposed that hot water acted as a modest acid catalyst, reactant, and solvent in the hydrolysis reactions.

Solid-phase synthesis of sn-1,2- and sn-2,3-diacylglycerols via ring-opening of the glycidyl-bound resin

A general method developed for the parallel solid-phase synthesis of sn-1,2- and sn-2,3-diacyglycerol derivatives. The technique relies on the use of carboxylic acid-promoted epoxide ring-opening reactions of the glycidyl-bound resin 3. The polymer-bound monoacylglycerol 5, formed in this manner, is transformed to the respective polymer-bound diacylglycerols 7 and 9 by reaction of the free alcohol moiety with a second carboxylic acid under conditions that lead to retention or inversion of C-2 stereochemistry. The sequence is completed by BCl3-promoted cleavage of 7 and 9 to form the sn-1,2- and sn-2,3-diacylglycerols, respectively.

Copper(II) tetrafluoroborate catalyzed ring-opening reaction of epoxides with alcohols at room temperature

[reaction: see text] Efficient ring opening of different epoxides by reaction with representative alcohols is presented. These processes were carried out at room temperature and rely on the usefulness of commercial copper tetrafluoroborate as catalyst.