ANTIVIRAL ACTIVITY OF GLYOXALS AND DERIVATIVES

Rapid, One-Step Synthesis of α-Ketoacetals via Electrophilic Etherification

Herein, we report a rapid, one-step synthesis of α-ketoacetals via electrophilic etherification of α-alkoxy enolates and monoperoxyacetals. Methyl, primary, and secondary α-ketoacetals were obtained in 44-63% yields from tetrahydropyranyl substrates; using methyl tetrahydropyranyl, alkyl tetrahydropyranyl, or methyl tetrahydrofuranyl peroxyacetals, however, methyl and primary products were isolated in 66-90% yields. The present method is applied to C-O bond formation at tertiary carbons, via alkyl and methyl peroxyacetals, with yields of 25-65%. Intermolecular "alkoxyl" transfer, from peroxyacetal to α-alkoxy enolate, relies heavily on decreased steric bulk surrounding the peroxide bond and site of etherification; additionally, we found the α-OCH₃ group to be critical in ensuring product formation. α-Ketoacetals demonstrated excellent reactivity, as selective, nucleophilic attack at the unprotected carbonyl furnished α-hydroxy acetals in 80-100% yields; subsequent hydrolysis of the foregoing compounds provided α-hydroxy aldehydes in yields of 58-90%.

1-{5-[2-Chloro-5-(trifluoromethyl)phenyl]thiophen-2-yl}ethanone

In the title molecule, C₁₃H₈ClF₃OS, the dihedral angle between the mean planes of 2-chloro-5-(trifluoro­meth­yl)phenyl and tiophene rings is 54.37 (5)°. The acethyl group is twisted by 8.1 (2)° with respect to the thio­phene ring. The CF₃ group is disordered over two sets of sites with occupations of 0.49 (3) and 0.51 (3). The crystal packing features C—H⋯F and C—H⋯O hydrogen bonds, forming dimers which are connected into chains along the c axis by C—H⋯O hydrogen bonds and C—Cl⋯π [Cl⋯π = 3.415 (1) Å and C—Cl⋯π = 151.56 (5)°] inter­actions. The chains are further connected into layers perpendicular to the a axis by C—H⋯O inter­actions.