R. Sidick Basha

Copper oxide nanoparticle mediated ‘click chemistry’ for the synthesis of mono-, bis- and tris-triazole derivatives from 10,10-dipropargyl-9-anthrone as a key building block

The synthesis of mono-, bis- and tris-triazole derivatives was accomplished using 10,10-dipropargyl-9-anthrone as a key starting material. Various acetylenic compounds (2–5) derived from 10,10-dipropargyl-9-anthrone on reaction with alkyl/benzyl bromides and sodium azide in the presence of 10 mol% of copper oxide nanoparticles along with 20 mol% sodium ascorbate in water afforded a wide variety of triazoles derivatives (8–13) under heating at 70 °C. The salient features of the present protocol are: mild reaction conditions, a shorter reaction time, the reusability of the catalyst, and its applicability with a wide range of substrates. Moreover, the mono-triazole 8b undergoes extended assembly in the solid state forming a zig-zag supramolecular structure stabilized by π–π and C–H⋯π interactions. Interestingly, the single crystal X-ray structure of 9b shows that it forms a supramolecular ball structure stabilized by a combination of C–H⋯O interaction and hydrogen bonding. Furthermore the presence of water molecules embedded in the crystal lattice of 9b allows these supramolecular balls to arrange in a chain generating a fascinating supramolecular architecture.

Synthesis of 2-triazolyl-imidazo[1,2-a]pyridine through a one-pot three-component reaction using a nano copper oxide assisted click-catalyst

The syntheses of 2-triazolyl imidazo[1,2-a]pyridine (8a–o) were accomplished through three component A3 coupling followed by 5-exo dig cyclisation by employing 1-alkyl-1,2,3-triazole-4-carbaldehyde, amidine and terminal alkynes using 5 mol% nanocopper oxide together with 10 mol% sodium ascorbate as a click-catalyst in ethanol at 70 °C. The present protocol was further utilized for the synthesis of 2-(2-triazolyl-imidazo[1,2-a]pyridin-3-yl)ethanol (9a–e). In addition, the molecular structure of 8c possesses a C–H⋯π interaction (H17b⋯C10) along with a peculiar supramolecular layered structure architecture. This protocol features ready recyclability of the catalyst, good yields and wide substrate scope. Moreover, the syntheses of triazolyl precursors (1-alkyl-1,2,3-triazol-4-yl)methanol (4a–f) have also been achieved through a nano copper oxide mediated click-catalyst in water at 70 °C.

A direct approach for the expedient synthesis of unsymmetrical ethers by employing bromodimethylsulfonium bromide (BDMS) mediated C–S bond cleavage of naphthalene-2-ol sulfides

The unsymmetrical ether derivatives 1-(alkoxy(aryl)methyl)naphthalen-2-ols (3a–q) were synthesized from 1-(aryl(alkyl/arylthio)methyl)-naphthalene-2-ol derivatives (1) and alcohols (2) by cleavage of C–S bond using bromodimethylsulfonium bromide (BDMS) at room temperature. Moreover, 1-(hydroxy(aryl)methyl)naphthalen-2-ol derivatives (7a–d) were also synthesized from the corresponding sulfide derivatives (1) on reaction with water using one equivalent BDMS. The direct synthesis of 3a was also achieved from β-napthol 5 by tuning the reaction conditions with overall one-pot two-steps sequence. Interestingly, the desired products 3a are not accessible directly from 2-naphthol, aromatic aldehyde and alcohol in the presence of BDMS at room temperature. Some of the salient features of this protocol are mild reaction conditions, good yields, operational simplicity and with a wide substrate scope.

VO(acac)2/H2O2/NaI: a mild and efficient combination for the cleavage of dithioacetal derivatives of sugars

A wide variety of dithioacetal derivatives of sugars can be cleaved easily into the corresponding open-chain aldehydo sugars using an efficient combination of VO(acac)(2)/H(2)O(2)/NaI at 0-5°C. Some of the salient features of this protocol are mild reaction conditions, good yields, short reaction times, easy work-up procedures, and non-involvement of toxic chemicals.

One-pot three-component regioselective synthesis of C1-functionalised 3-arylbenzo[f]quinoline

An efficient method for regioselective synthesis of C1-functionalised 3-arylbenzo[f]quinoline has been demonstrated via γ-selective aromatization using β-ketoester, 2-naphthylamine and aromatic aldehyde by employing 10 mol% camphorsulfonic acid as the catalyst in acetonitrile at 70 °C. In this approach, two C–C bond formations will result in functionalised benzo[f]quinoline in a one-pot three-component reaction. In addition, the present protocol has a diverse substrate scope with good yields. Furthermore, the protocol was directly utilised for the synthesis of alkyl 2-(3-(naphthalen-2-yl)benzo[f]quinolin-1-yl)acetate, allyl 2-(3-(heteroaromatic)benzo[f]quinolin-1-yl)acetate and functionalised 1,2,3-trisubstituted benzo[f]quinoline.