Search

A simple protocol to synthesize indenes efficiently by PTSA catalyzed tandem Friedel–Crafts alkylation/hydroarylation of tertiary propargylic alcohol with electron-rich arenes is described. The desired indenes were obtained regioselectively in good to very good yields under mild reaction conditions. The allene intermediate was isolated to get an insight into the mechanistic pathway of the indene forming reaction.

A facile iron-catalyzed dual C–C bond cleaving reaction involving 1,3-dicarbonyl units along with electron-rich and sterically bulky arenes as efficient carbon-based leaving groups has been developed. The scope of the dual C–C bond breaking reaction was studied in detail using a range of nucleophiles to synthesize symmetrical triarylmethanes in good to excellent yields. We found success in isolating the intermediate of the reaction, formed via the initial Csp3–Csp3 bond cleavage, and subsequently converted the intermediate to the final product via the Csp3–Csp2 bond cleavage. A notable difference in the leaving aptitudes of the two carbon-based leaving groups perceived during the study enabled us to develop an application of the dual C–C bond breaking reaction for the synthesis of unsymmetrical triarylmethanes in a stepwise manner. To improve the synthetic utility, we have also fashioned a one-pot procedure to generate unsymmetrical triarylmethanes via sequential C–C bond breaking reactions. In addition to studying a novel dual C–C bond breaking reaction and providing a hint to the mechanistic pathway, the application molded from the study for the synthesis of symmetrical and especially unsymmetrical triarylmethanes may render value to the present work.

Active Sn(0) particles are synthesized in high yields by the chemical reduction of the blue–black stannous oxide using freshly prepared sodium stannite solution as reducing agent at 40 °C and 60 °C. The Sn(0) particles are characterized using powder XRD, SEM, and DSC. The as-synthesized Sn(0) particles are applied as reagent for the regioselective synthesis of homopropargyl alcohols from propargyl bromide and aldehydes in distilled water at room temperature (in 50%–84% yields). No assistance of heat, microwave, ultrasound, organic co-solvent, co-reagent, or inert atmosphere is required for this reaction. The propargylation reaction is highly chemoselective towards aldehyde over other less electrophilic carbonyl functional groups such as ketone, amide, and carboxylic acid. Our in-house synthesized homopropargyl alcohols can be used to synthesize conjugated 1,3-diynes.

Active bismuth is synthesized by the chemical reduction of bismuth trichloride using freshly prepared sodium stannite solution as the reducing agent at room temperature. The as-synthesized active bismuth is applied as a reagent for the synthesis of homoallyl alcohol/homopropargyl alcohol from allyl bromide/propargyl bromide and carbonyl compounds in water at $$50\,{^{\circ }}\hbox {C}$$ . The homoallyl amines are also synthesized from N-tosyl aldimines and allyl bromide using active bismuth reagent in good yields. No assistance of organic co-solvent, co-reagent, phase transfer catalyst or inert atmosphere is required for this reaction. The waste bismuth material obtained after the completion of the organic reaction can be reduced to active bismuth by sodium stannite solution and successfully reused for mediating the allylation of aldehydes. Synopsis Active bismuth mediated allylation/crotylation of aldehydes is developed in water to get homoallyl alcohols. The method is also applied for the allylation of N-tosyl aldimines and propargylation of aldehydes in water to achieve the homoallyl amines and homopropargyl alcohols, respectively. The reactions do not require the assistance of organic co-solvent, co-reagent, phase transfer catalyst or inert atmosphere.