Mild and selective reduction of aldehydes utilising sodium dithionite under flow conditions

Abstract

We recently reported a novel hybrid batch–flow synthesis of the antipsychotic drug clozapine in which the reduction of a nitroaryl group is described under flow conditions using sodium dithionite. We now report the expansion of this method to include the reduction of aldehydes. The method developed affords yields which are comparable to those under batch conditions, has a reduced reaction time and improved space-time productivity. Furthermore, the approach allows the selective reduction of aldehydes in the presence of ketones and has been demonstrated as a continuous process.

A facile and highly efficient transfer hydrogenation of ketones and aldehydes catalyzed by palladium nanoparticles supported on mesoporous graphitic carbon nitride

“…All 1 H NMR data of the alcohols were in agreement with the reported spectra. 5,[26][27][28][29][30][31][32][33][34] 1-(4-Methoxyphenyl)ethan-1-ol (2a): 1 26 1-(4-Fluorophenyl)ethan-1-ol (2d): 1 H NMR (400 MHz, CDCl 3 ): δ = 7.36-7.32 (m, 2H), 7.06-7.01 (m, 2H), 4.88 (q, J = 6.4 Hz, 1H), 1.48 (d, J = 6.4 Hz, 3H). 29 1-(4-Chlorophenyl)ethan-1-ol (2e): 1 H NMR (400 MHz, CDCl 3 ): δ = 7.36-7.26 (m, 4H), 4.87 (q, J = 6.4 Hz, 1H), 1.46 (d, J = 6.4 Hz, 3H).…”

Vinylene Carbonate as Latent Formylmethyl Surrogate: The Expediency of Ruthenium(II) Catalysis in Accessing Arylacetaldehydes, Arylacetates and Acetals

“…Aldehydes are an important class of carbonyl compounds and are repetitive structural motifs in natural products, clinical candidates and functional materials [4] . Along this line, their supremacy is further validated by formylmethyl group which is of great attention in organic synthesis, as the formyl group undergoes functional group interconversion by means of Wittig reaction, [5] oxidation, [6] reduction, [7] aldol reaction, [8] reductive amination, [9] umpolung reactions, [10] and so forth. The existing approaches for construction of formylmethyl group relies on employment of one carbon unit such as carbon monoxide, N , N ‐dimethylformamide (DMF) with aryl methyl halides [11] .…”

Sonochemical and Mechanochemical Synthesis of Alcohols from Aldehydes and Ketones

“…Reduction of aldehydes or ketones is considered a simple and straightforward method to synthesize alcohols. Various reductants have been utilized in this reaction, for example, ZrOCl 2 [14], Na 2 S 2 O 4 [15], Zn/NH 4 Cl [16], ammonia borane [17], LiAlH 4 [18], Zn(BH 4 ) 2 [19], and NaBH 4 [20][21]. The reduction using NaBH 4 is considered convenient and simple since it can be carried out under milder conditions and does not require specific equipment.…”