Chitosan: a highly efficient renewable and recoverable bio-polymer catalyst for the expeditious synthesis of α-amino nitriles and imines under mild conditions

Abstract

Commercial chitosanwithout any post-modification with active Bronsted or Lewis acid centerswas found to be a highly efficient renewable and recoverable bio-polymer catalyst for the rapid and convenient synthesis of α-amino nitriles or imines from aromatic aldehydes and amines under mild reaction conditions at room temperature in high to quantitative yields. The α-amino nitrile derivatives were prepared through the Strecker reaction using trimethylsilyl cyanide (TMSCN) and catalyzed by chitosan as a heterogeneous bifunctional organocatalyst.Scheme 1 Chemical structure of chitosan (1a) and chitin (1b). † Electronic supplementary information (ESI) available: Experimental details, IR and 1 H NMR spectral data for some of the prepared imines. See

Organocatalytic clean synthesis of densely functionalized 4H-pyrans by bifunctional tetraethylammonium 2-(carbamoyl)benzoate using ball milling technique under mild conditions

“…However, the use of phthalimide-N-oxyl (PINO) anion with different counter cations at 10 mol% loading slightly improved the yield of desired product 9a under ball milling Scheme 4. One-pot three-component reaction of resorcinol (12), aldehydes (7a-m), and malononitrile (8) catalyzed by TEACB (5) using the ball milling technique at ambient temperature. Table 4.…”

“…Table 4. Three-component synthesis of different 2-amino-7-hydroxy-4H-chromene-3-carbonitrile derivatives (13a-j) via condensation of resorcinol (12), aldehydes 7a-m, malononitrile (8) in the presence of TEACB (5) conditions. POPINO afforded higher yield compared to other salts including Li + and Na + (Entries 2-4, Table 1).…”

“…On the other hand, the 4H-pyran derivatives show various pharmacological properties such as spasmolytic, diuretic, anticoagulant, anticancer, and antianaphylactic activities (9,(10)(11)(12). Such diverse biological features have made 4H-pyran derivatives important for further exploration in modern medicinal and combinatorial chemistry (46,47).…”

“…Their superior atom economy, resulting in substantial minimization of waste, labour, time, and cost as well as high efficiency, mild conditions, high convergence, and their general compatibility with green solvents, would justify a central place in the toolbox of green synthetic methodologies (5)(6)(7)(8). Therefore, academic and industrial research groups have increasingly focused on the use of MCRs for synthesizing a broad range of products especially important heterocyclic compounds such as 4H-pyran derivatives nowadays (9,(10)(11)(12). Recently, several techniques for efficient application of solvent-free conditions or MCRs have been developed individually.…”

A facile and environmentally benign polyethylene glycol 600-mediated method for the synthesis of densely functionalized 2-aminothiophene derivatives under ultrasonication

“…Lower reaction and purification steps, and high atom economy as well as highly convergent and requiring minimum time compared to multi-step alternative synthetic routs make MCRs good candidates for green organic processes (12)(13)(14)(15)(16)(17)(18)(19). The Gewald reaction is a popular catalytic and one-pot three-component reaction between elemental sulfur, a cyanomethylene containing an electron-withdrawing group and an enolizable carbonyl compound that affords highly substituted 2-aminothiophene derivatives (12,20).…”