A concise synthesis of isatin-based aromatic compounds in water as the reaction medium resulting in an approach to green chemistry

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

“…High yields (70-90%), recyclability, and reusability of the synthesized catalyst are some of the main advantages of this method. 214 Nano-Ni(II)/Y zeolite, as a non-toxic heterogeneous catalyst, at 60 C under solvent-free conditions also accelerated this transformation within 46-122 min in good to excellent 79-99% yields. 215 In 2013, Wang and co-workers developed a simple and efficacious process for the synthesis of benzimidazole-based Nheterocyclic carbenes (222) via the cyclization of N,N 0 -diarylaryldiamines (221), arising from aryldiamines (220), with TMOF (4) using concentrated HCl and formic acid at 80 C for 2 h in 88-97% yields (Scheme 59).…”

“…High yields (70–90%), recyclability, and reusability of the synthesized catalyst are some of the main advantages of this method. 214 Nano-Ni( ii )/Y zeolite, as a non-toxic heterogeneous catalyst, at 60 °C under solvent-free conditions also accelerated this transformation within 46–122 min in good to excellent 79–99% yields. 215 …”

“…218, respectively, by catalytic amounts of ZrOCl 2 $8H 2 O under solvent-free conditions at room temperature or 85 C for short reaction times (4-12 min) and moderate to excellent yields (83-97%) (Scheme 58). 212 In 2018, ZrOCl 2 $8H 2 O@nano SiO 2 as a new catalyst was originated and characterized and subsequently its catalytic activity (0.01 g) has been investigated for the preparation of benzimidazoles 213,214 via the condensation reaction of trialkyl orthoformates with diamines under solvent-free condition at 60 C within reaction times of 1.5-5.5 h and 70-90% yields. High yields (70-90%), recyclability, and reusability of the synthesized catalyst are some of the main advantages of this method.…”

“…Maleki et al synthesized and characterized Ag (1.5%)@TiO 2 (0.1 mL) as a heterogeneous, hazardless, eco-friendly, and reusability nanocatalyst. Then its catalytic activity was examined for the preparation of benzoxazole 214,307 via the condensation reaction of orthoesters with 2-amino phenol in water at room temperature within very short reaction times (4-10 min) and at excellent yields (82-93%). 307…”

Nanocatalyzed Synthesis of Benzoxazoles

“…Reusability was demonstrated in 4 rounds without degradation in catalyst potential. [68] R. Gupta et al ( 2017) used a one-pot condensation reaction between substituted o-aminophenol (81) and benzoyl chlorides (82) in the presence of CuÀ Al hydrotalcite nano-catalysts (nano-Cu-Al hydrotalcite, Table 3, Entry 2) under the neat circumstance of a controlled temperature of 60 °C to show an environmentally friendly rapid technique for the synthesis of several benzoxazole compounds (83) (Scheme 27). The present nanocatalyst was constructed by the co-precipitation methodology and the structures of the catalysts were confirmed by XRD, FTIR, SEM, and TG.…”