Md. Taifur Rahman

Spurring radical reactions of organic halides with tin hydride and TTMSS using microreactors.

Tributyltin hydride-mediated radical reactions of organic halides were successfully carried out in a continuous flow system using a microreactor. The reactions proceeded within a very short period of time, coupled with quickly decomposing radical initiators such as V-65 and V-70. The continuous flow reaction system was applied to gram scale synthesis of a key intermediate for furofuran lignans.

Microflow radical carboaminoxylations with a novel alkoxyamine.

Highly efficient thermal radical carboaminoxylations of various olefins by using the novel alkoxyamine A to give adducts of type B are described. It is reported that these radical addition reactions can be performed in a microflow reaction system. As compared to conventional batch reaction setup, significantly higher yields are obtained by running carboaminoxylations using the microflow system under analogous conditions.

Radical carbonylations using a continuous microflow system

Summary Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

Synthesis of 4,4-bis(2-hydroperoxyalkyl)pyrazolidine-3,5-diones using manganese(III)-catalyzed autoxidation

Abstract The autoxidation of a mixture of 1,2-disubstituted pyrazolidine-3,5-diones 1 and alkenes 2 in the presence of a catalytic amount of manganese(III) acetate dihydrate in air gave 4,4-bis(2-hydroperoxyalkyl)pyrazolidine-3,5-diones 3 in 75–96% yields. The structure of the bis(2-hydroperoxyethyl)pyrazolidine-3,5-dione 3 (R1=R2=Ph, R3=R4=4-FC6H4) has been corroborated by an X-ray single crystallographic analysis. On the other hand, the manganese(III) acetate oxidation of a mixture of 1 (R1=R2=Ph) and 2 (R3=R4=Ph) at elevated temperature gave 4,4-bis(2,2-diphenylethenyl)-1,2-diphenylpyrazolidine-3,5-dione ( 4 ) in good yield.

Mn(III)-Initiated Facile Oxygenation of Heterocyclic 1,3-Dicarbonyl Compounds

The Mn(III)-initiated aerobic oxidation of heterocyclic 1,3-dicarbonyl compounds, such as 4-alkyl-1,2-diphenylpyrazolidine-3,5-diones, 1,3-dialkylpyrrolidine-2,4-diones, 3-alkyl-1,5-dimethylbarbituric acids, and 3-butyl-4-hydroxy-2-quinolinone gave excellent to good yields of the corresponding hydroperoxides, which were gradually degraded by exposure to the metal initiator after the reaction to afford the corresponding alcohols. The synthesis of 30 heterocyclic 1,3-dicarbonyl compounds, the corresponding hydroperoxides and the 10 alcohols, their characterization, and the limitations of the procedure are described. In addition, the mechanism of the hydroperoxidation and the redox decomposition of the hydroperoxides are discussed.

Continuous Microflow Bromination of Alkenes Combined with a Circulatory Recycling of a Fluorous Polyether as a Bromine Support

Fluorous multi-phase bromination reaction of alkenes could be successfully transformed to a continuous microflow system in which a fluorous polyether, Galden® HT135, is employed as a recyclable molecular bromine support. This microflow bromination of alkenes could be carried out without any temperature control or an inert gas atmosphere. The circulatory continuous microflow reaction system for bromination of cyclohexene was created which gave 8.3 g (85%) of dibromocyclohexane after continuous operation for 6 h.

Ionic liquids are not innocent in Pd catalysis. C–H arylation of thiazolium and imidazolium ionic liquids with aryl halides

The ionic liquids bearing an aromatic vinylic C–H moiety are not innocent during Pd-catalyzed cross-coupling reactions of aryl halides, since palladium-catalyzed direct C–H arylation of thiazolium and imidazolium ionic liquids competes.