Montmorillonite K10 Clay-Microwave Assisted Isomerisation of Acetates of the Baylis-Hillman Adducts: A Facile Method of Stereoselective Synthesis of (E)-Trisubstituted Alkenes

Abstract

Montmorillonite K10-microwave assisted stereoselective isomerisation of acetates of the Baylis-Hillman adducts furnished (E)-trisubstituted alkenes in high yields. A comparative study of this reaction with Mont-K10, ion-exchanged clay (Fe 3+ -Mont-K10) and acid treated regional natural Kaolinite clay and the efficiency of these clays in this reaction is described.

Recent Advances in the Baylis−Hillman Reaction and Applications

“…Subsequently, stereoselective isomerization of acetates of the Baylis−Hillman adducts have also been achieved by Shanmugam and Singh using the montmorillonite K10 clay microwave to furnish the ( E )-trisubstituted alkenes in high yields (eq 76) …”

Palladium-Catalyzed Cross-Coupling of Baylis−Hillman Acetate Adducts with Organosilanes

“…The reaction is highly stereoselective. The stereochemistry of the products was established by comparing NMR parameters for the olefinic and methylene protons for the products with literature values . The ratio of E / Z isomers was determined by 1 H NMR analysis.…”

Studies on montmorillonite K10-microwave assisted isomerisation of Baylis–Hillman adduct. Synthesis of E-trisubstituted alkenes and synthetic application to lignan core structures by vinyl radical cyclization

“…However, when a slurry of the acetate 2a with 50% w/w mont-K10 clay without any solvent was irradiated in a microwave oven for 6 min, a clean isomerised product 3a was obtained in 60% yield (w10% decomposition to aldehyde) as determined by 1 H NMR spectroscopy. Among the several variations tested to optimize the condition, 22 the condition involving acetate 2a with 30% w/w of mont-K10 clay, 70% microwave power level (PL) and 13 min. irradiation time was found to be the best and yielded the clean isomerised product 3a (in 9:1, E:Z isomer) in 74% after column purification.…”

“…Montmorillonite K10-microwave combination has been utilized for carrying out many organic transformations as a catalyst. [16][17][18] In continuation of our research on clay catalysis [19][20][21][22][23] in organic synthesis, herein we give an account on the mont-K10-microwave assisted stereoselective isomerisation of acetates of Baylis-Hillman adducts, a one-pot protectionisomerisation with trimethyl orthoformate and unsaturated alcohols. A synthetic application of propargyl derivatives of the Baylis-Hillman adduct thus obtained, in the synthesis of lignan core structures through a vinyl radical cyclization, have also been explored.…”