One‐pot synthesis of α‐aminophosphonates catalyzed by boric acid at room temperature

Boric acid-catalyzed multi-component reaction for efficient synthesis of 4H-isoxazol-5-ones in aqueous medium

“…Recently, this reagent has been used in various reactions including aza-Michael reaction [20], transesterification of ethyl acetoacetate [21], oxidation of sulfides [22], Biginelli reaction [23], and Mannich reaction [24]. In addition, it has also been used for the preparation of compounds such as the synthesis of 1,5-benzodiazepine derivatives [25], 2-amino-3,5-dicarbonitrile-6-thio-pyridines [26], 1-amidoalkyl-2-naphthols [27], dibenzoxanthenes [28], a-aminophosphonates [29], b-acetamido ketones [30], and a-hydroxyamides [31].…”

Synthesis of 1-amidoalkyl-2-naphthols based on a three-component reaction catalyzed by boric acid as a solid heterogeneous catalyst under solvent-free conditions

“…As a consequence of our interest in the application of solid acid catalysts in organic synthesis [17][18][19][20], herein, we describe an efficient method for the synthesis of 1-amidoalkyl-2-naphthols by one-pot condensation reaction of 2-naphthol, aldehydes and amides using catalytic amounts of boric acid under solvent-free conditions (Scheme 1).…”

“…Boric acid (H 3 BO 3 ) is a useful and environmentally benign catalyst which has been successfully utilized in numerous reactions [21][22][23][24][25][26][27][28][29], for example, the aza Michael addition [26], the Biginelli reaction [27], transesterification of ethyl acetoacetate [28], the Mannich reaction [29] and by our group in the synthesis of dibenzoxanthenes [17], α-aminophosphonates [18], dihydroquinazolinones [19] and benzimidazoles [20]. It offers milder conditions relative to common mineral acids.…”

Efficient, One‐Pot Synthesis of Tetrahydrobenzo[a]xanthen‐11‐ones and Dibenzo[a,j]xanthenes Using Trichloroacetic Acid as a Solid Heterogeneous Catalyst Under Solvent‐Free Conditions

“…In this context some methods and catalysts have been reported [7][8][9][10][11][12] . Furthermore, the synthesis of 14H-dibenzo[a,j]xanthenes and its analogous can be prepared by reaction of 2-naphthol with aldehydes in the presence of a catalyst [13][14][15][16][17] . However, these methodologies show varying degrees of success as well as limitations due to use of toxic organic solvents, expensive catalyst, prolonged reaction times, the requirement of special apparatus, or harsh reaction conditions.…”

“…Following our systematic studies directed towards the development of practical, safe, and environmentally friendly procedures for several important organic transformations [17][18][19] , we describe an efficient method for the synthesis of tetrahydrobenzo[a]xanthen-11-ones through three-component reactions of aldehydes, 2-naphthol and dimedone using trichloroacetic acid (CCl 3 COOH) as a catalyst under solvent-free conditions (Scheme 1-2). …”