Synthesis of fused pyridines in the presence of thiamine hydrochloride as an efficient and reusable catalyst in aqueous conditions

An eco-compatible synthesis of novel spiro[acenaphthylene-1,2′[1,3]-thiazolidine]-2,4′(1H)-diones using thiamine hydrochloride as efficient catalyst in aqueous medium

“…Firstly, there is Role of the VB1-as a catalyst may be postulated in terms of the acidic CH proton leading to its interaction with the heteroatoms, thereby increasing polarization and promoting the condensation reaction [62,63].…”

Chitosan: an efficient promoter for the synthesis of 2-aminopyrimidine-5-carbonitrile derivatives in solvent free conditions

“…In view of the above considerations, and on the basis of our progressive endeavours in exploring green protocols for the synthesis of heterocyclic frameworks, 22 herein we wish to uncover a more practical and expedient synthesis of 2-aminopyrimidine derivatives by using aldehydes (1) guanidines ( 2), and cyanoketones (3), under solvent free conditions at 85 1C, in the presence of chitosan without any post modification (Scheme 1).…”

An Efficient Protocol for the Synthesis of Pyrido[2,3‐d]pyrimidines in Glycerol–Water Medium: Assessment by Green Chemistry Metrics

“…[18] Consequently, a number of synthetic approaches have been reported for the preparation of pyrido [2,3d]pyrimidine derivatives. [19][20][21][22] Moreover, the literature survey reveals that pyrido [2,3-d]pyrimidines are usually synthesized by condensation of aromatic aldehyde, malononitrile, and 6-aminouracil or its derivatives at different reaction conditions such as 1) tetra-n-butyl ammonium bromide (TBAB)/ ultrasonic irradiation/water/70°C/50 min; [23] 2) triethylbenzylammonium chloride (TEBAC)/water/90°C/6-10 h; [24] 3) nanocrystalline MgO/water/80°C/12-35 min; [25] 4) KF-Al 2 O 3 /ethanol/90°C/5-8 h; [26] 5) diammonium hydrogen phosphate (DAHP)/water-ethanol/reflux/2 h; [27] 6) DMF/reflux/ 20-30 h; [28] 7) NaBr/ethanol or acetonitreile/electrolysis/25-30 min; [29] 8) SBA-Pr-SO 3 H/solvent free/5-45 min; [30] 9) Al-HMS-20/ethanol/RT/12 h [31] ; and 10) thiamine hydrochloride/water/90°C/2-2.5 h. [32] By considering the pharmacological significance of pyrido [2,3d]pyrimidines and within the framework of green chemistry approach for the expansion of our previous success, [33] we herein report a clean, efficient, and ecofriendly protocol for the glycerolassisted catalyst-free synthesis of pyrido[2,3-d]pyrimidine derivatives by one-pot three-component condensation of aromatic aldehyde, malononitrile, and 6-aminouracil or 6-amino-1,3dimethyluracil (Scheme 1).…”

“…Consequently, a number of synthetic approaches have been reported for the preparation of pyrido[2,3‐ d ]pyrimidine derivatives . Moreover, the literature survey reveals that pyrido[2,3‐ d ]pyrimidines are usually synthesized by condensation of aromatic aldehyde, malononitrile, and 6‐aminouracil or its derivatives at different reaction conditions such as 1) tetra‐ n ‐butyl ammonium bromide (TBAB)/ultrasonic irradiation/water/70 °C/50 min; 2) triethylbenzylammonium chloride (TEBAC)/water/90 °C/6‐10 h; 3) nanocrystalline MgO/water/80 °C/12‐35 min; 4) KF‐Al 2 O 3 /ethanol/90 °C/5‐8 h; 5) diammonium hydrogen phosphate (DAHP)/water‐ethanol/reflux/2 h; 6) DMF/reflux/20‐30 h; 7) NaBr/ethanol or acetonitreile/electrolysis/25‐30 min; 8) SBA–Pr–SO 3 H/solvent free/5‐45 min; 9) Al–HMS‐20/ethanol/RT/12 h; and 10) thiamine hydrochloride/water/90 °C/2‐2.5 h …”