A green protocol for one-pot three-component synthesis of 1-(benzothiazolylamino) methyl-2-naphthol catalyzed by oxalic acid

Recent advances in the synthesis and synthetic applications of Betti base (aminoalkylnaphthol) and bis-Betti base derivatives

“…A green protocol for one-pot three-component synthesis of 1-(benzothiazolylamino)methyl-2-naphthols 129 via the reaction of aromatic aldehydes, 2-naphthol and 2-aminobenzothiazole catalyzed by oxalic acid (20 mol%) under thermal and solventfree conditions is described by Maghsoodlou et al The reaction was carried out under solvent-free condition at 80 C for 4-30 min to give the corresponding products in 57-98% yields (Scheme 87). 96 The direct three-component reaction via condensation of aldehydes, 2-naphthols and piperidine has been reported, generating 1-(aryl(piperidin-1-yl)methyl)naphthalene-2-ol derivatives 130 over Fe 3 O 4 magnetic nanoparticles with high efficiency (90-97% yields) under ultrasound irradiation (frequency of 40 kHz and an input power of 600 W) and solventfree condition at 80 C for 20-25 min (Scheme 88). 97 Aza-Friedel-Cras reaction of N-alkoxycarbonyl isatin ketimines with naphthols using a new 2-adamantyl-substituted quinine-derived squaramide catalyst (2 mol%) and 25 mg 4Å molecular sieve in CH 2 Cl 2 at À20 C for 12-48 h afforded chiral tetrasubstituted 3-amino-2-oxindoles 131 and 132 with excellent enantioselectivity up to greater than 99% ee and in 61-99% yields (Scheme 89).…”

α-Aminoazoles/azines: key reaction partners for multicomponent reactions

“…This strategy involves heating an aqueous mixture of 2-naphthol 406, aldehydes 4 and 2-aminobenzothiazole 3b together with 20 mol% of SDS at 100 °C for 1–3 h, resulting in the construction of C–C and C–N bonds. 235 Since then, a number of reactions have been carried out for the synthesis of 1-(benzothiazolylamino)methyl-2-naphthol derivatives 407 based on the same platform with the help of catalysts/promoters such as NaHSO 4 ·H 2 O, 236 heteropolyacid (HPA) as a heterogenous catalyst, 237 rice husk ash (RHA)-supported 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sulfate (RHA-[pmim]HSO 4 ) as an acidic ionic liquid, 238 KOH-loaded MgO/hydrotalcite as a basic catalyst, 239 oxalic acid as an organocatalyst, 240 MPIL B, 241 NH 3 (CH 2 ) 5 NH 3 BiCl 5 , 242 Fe 3 O 4 @SiO 2 -Propyl-Pip-SO 3 H·HSO4, 243 γ-aminobutyric acid and isinglass a collagen peptide, 244 Fe 3 O 4 @SiO 2 @(CH 2 ) 3 -urea-SO 3 H/HCl, 245 Fe 3 O 4 @SiO 2 –ZrCl 2 -MNPs, 246 and (rMGO)-Au NPs 247 ( Scheme 135 ). The reaction mechanism for the formation of Betti's base proceeds though an o -QM intermediate 407a, which is generated from the condensation of 2-naphthol with aldehyde in the presence of a suitable catalyst.…”

Fe3O4@MCM‐41@ZrCl2: A novel magnetic mesoporous nanocomposite catalyst including zirconium nanoparticles for the synthesis of 1‐(benzothiazolylamino)phenylmethyl‐2‐naphthols

“…[46][47][48] The extensive and significant role of 2-aminobenzothiazole core, as a privileged scaffold, in pharmaceutical, biological, and industrial chemistry is undeniable. [49][50][51][52][53][54][55][56][57][58] Among these types of compounds, 1-(benzothiazolylamino)phenylmethyl-2-naphthols have two biologically active components, 2-aminobenzothiazole and a Betti's base. Betti's base, a structure called 1-(α-aminoalkyl)-2-naphthols with two active amino and hydroxyl groups, plays a major role in synthetic chemistry due to the possibility of C-C bond formation under mild laboratory conditions.…”

“…Betti's base, a structure called 1-(α-aminoalkyl)-2-naphthols with two active amino and hydroxyl groups, plays a major role in synthetic chemistry due to the possibility of C-C bond formation under mild laboratory conditions. [58] These benefits have navigated numerous efforts to synthesize 1-(benzothiazolyl amino)phenylmethyl-2-naphthols employing various catalysts such as sodium dodecyl sulfate (SDS), [59] NaHSO 4 .H 2 O, [60] heteropolyacid (HPA), [61] maltose, [62] 3-methyl-1-(4-sulfonic acid) propylimidazolium hydrogen sulfate [(CH 2 ) 3 SO 3 HMIM] [HSO 4 ], [63] fumaric acid, [64] oxalic acid, [58] ɤ-aminobutyric acid (GABA), [65] phosphate fertilizers, [66] and NH 3 (CH 2 ) 5 NH 3 BiCl 5 . [67] Although all reports have their own credits, some defects such as toxicity and expensiveness of the catalyst, environmental pollution, challenging synthesis, inaccessible reactions, long-term reaction times, and undesirable yields are still notable.…”