The Baylis-Hillman reaction: a novel concept for creativity in chemistry

This tutorial review highlights the way in which the Baylis-Hillman reaction has been increasingly attracting the attention of synthetic and medicinal chemists; it not only helps in originating new ideas to create novel methodologies and molecules but also offers intellectual challenges to understand and address the present day needs in the areas of organic and medicinal chemistry.     

Anthecularin: a novel sesquiterpene lactone from Anthemis auriculata with antiprotozoal activity

Anthecularin (1), a minor sesquiterpene lactone with a novel ring system was isolated from Greek Anthemis auriculata (Asteraceae). Its structure was elucidated by means of NMR, HRMS, and X-ray crystallography. Anthecularin showed antitrypanosomal (IC50=10.1 microg/mL) and antiplasmodial activity (IC50=23.3 microg/mL) and inhibited two key enzymes of the plasmodial type II fatty acid biosynthesis pathway, PfFabI and PfFabG (IC50 values=14 and 28.3 microg/mL, respectively). A probable biogenesis of 1 is also proposed and discussed.     

The reaction of Grignard reagents with 1,3-dioxolanes : III. A novel synthetic route to β-hydroxyalkyl enol ethers

The reaction of ethylmagnesium bromide, prepared in benzene with one or more molar equivalents of triethylamine, with 2-, 2,4- and 2,4,5-substituted 1,3-dioxolanes has been investigated. Besides β-hydroxyethyl sec-alkyl ethers, the normal products of the ring opening/addition reaction encountered with other Lewis bases, 2-hydroxyethyl enol ethers were formed as products of a ring opening/elimination reaction. Kinetic studies suggest an E₁ mechanism for this novel reaction.     

The Baylis-Hillman reaction in supercritical carbon dioxide: enhanced reaction rates,unprecedented ether formation,and a novel phase-dependent 3-component coupling

The Baylis-Hillman reaction can be efficiently carried out in scCO2 with enhanced reaction rates relative to comparable solution phase reactions; at low pressures, a novel dimerisation is observed which has led to the development of a novel one-pot three component coupling reaction to form highly functionalized ethers.     

Electron ionization and methane chemical ionization mass spectrometry study of some 2,2-disubstituted 1,3-dioxolanes, 1,3-dithiolanes, 1,3-oxathiolanes and 1,3-dioxanes. Gas-phase lactone and thiolactone formation

The electron ionization and methane chemical ionization mass spectra of some 2,2-disubstituted 1,3-dioxolanes, 1,3-dithiolanes and 1,3-oxathiolanes were studied. Especially, the effect of the length of the side chain in ring position 2 of these compounds and the ease of formation of possible lactone/thiolactone ion as a fragmentation product were examined. In addition, two 2,2-disubstituted 1,3-dioxanes were studied to see the effect of the bigger ring size. The formation of lactone ions was more favorable under methane chemical ionization than under electron ionization conditions. The structures of fragment ions and the ions generated from model compounds were carefully studied using both high- and low-energy collision-induced dissociation. Also ab initio molecular orbital calculations up to the HF/6–31G** level of theory for protonated 2-methyl-2-propanoic acid ethyl ester of 1,3-dioxolane, 1,3-oxathiolane and 1,3-dithiolane and for two isomeric bicyclic ions were carried out. The theoretical results obtained favor the formation of the lactone ion. Copyright © 2005 John Wiley & Sons, Ltd.     

The structure of a sesquiterpene lactone from Artemisia fragrans

Summary From the epigeal part ofArtemisia fragrans Willd. a new sesquiterpene lactone C₁₅H₂₀O₄ has been isolated which has been called alkhanin.It has been shown that alkhanin has the structure (I).V. L. Komarov Institute of Botany, Academy of Sciences of the Azerbaidzhan SSR, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 75–77, January–February, 1978.     

A novel antileukemic sesquiterpene lactone. Synthesis of racemic eriolanin

The synthesis of dl-eriolanin 1, highly oxygenated 1,10-seco-eudesmanolide isolated from the chloroform extracts of Eriophyllum lanatum Forbes (Compositae), is reported.     

The structure of the sesquiterpene lactone saupirin

Conclusions A new sesquiterpene lactone, saupirin, has been isolated from the epigeal green part ofSaussurea neopulchella Lipsch. andSaussurea pulchella Fisch., and structure (I) has been proposed for it.All-Union Scientific-Research Institute for Medicinal Plants. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 727–736, November–December, 1971.     

Dendocarbin A: a sesquiterpene lactone from Drimys winteri

The natural compound dendocarbin A, C₁₅H₂₂O₃, is a sesquiterpene lactone isolated for the first time from Drimys winteri for var chilensis. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ and its X‐ray crystal structure confirmed the S/R character of the chiral centres at C‐5/C‐10 and C‐9/C‐11, respectively. The α‐OH group at C‐11 was found to be involved in intermolecular hydrogen bonding, defining chains along the <100> 2₁ screw axis.     

The rapid photomediated alkenylation of 2-alkyl-1,3-dioxolanes with alkynes: A stereoelectronically assisted chain reaction

The photomediated reaction of alkynes such as DMAD with 1,3-dioxolanes leads to remarkably rapid alkenylation; evidence is presented that these reactions occur via a chain mechanism.     

Conformation of gallicin,a ten-membered-ring sesquiterpene lactone

Conformation 8 was assigned to gallicin on the basis of NOE effect, variable-temperature ¹H-NMR, LIS and chemical data interpretation.