Studies Concerning the Use of Activated Alkenes in Enantioselective Reactions.
A brief overview of the cinnamate esters equivalents and their behaviour under organocatalysis and metal catalysis.
The addition of bisulfite to olefins, discovered over a century ago, remains the most straightforward approach to aliphatic sulfonic acids. A catalytic enantioselective procedure has now been realized that employs a bifunctional aminothiourea catalyst. Sulfonic acids were obtained from chalcones in high yields and high enantioselectivity and in both configurations.
The use of 3-phenyl-5-vinyl-1,2,4-oxadiazole as activated alkene for the Morita-Baylis-Hillman reaction in presence of one equivalent of 1,8-Diazabicycloundec-7-ene gave good yields with several aldehydes bearing both aromatic and aliphatic substituent.
The asymmetric Michael addition of nitromethane to a series of 5-Vinyl-1,2,4-Oxadiazole promoted by cinchona alkaloids ammonium salts gave corresponding nitroadducts in medium-good yield but poor ee. Hydrolysis of nitroadduct, to unveil corresponding cinnamic acid, was performed successfully. This study can be extended to the addition of others nucleophiles to 5-Vinyl-1,2,4-Oxadiazole.
Diels-Alder reaction of dienophile 3-phenyl-5-vinyl-1,2,4-oxadiazole with several diene in presence of catalytic amount of Cu(OTf)2 gave good yield and excellent endo:exo ratio.