Novel Petasis boronic acid-Mannich reactions with tertiary aromatic amines

Tertiary aromatic amines can serve as amine substrates for the Petasis boronic acid-Mannich reaction, providing a practical synthetic route for the CC bond formation of α-(4-N,N-dialkylamino-2-alkyloxyphenyl)carboxylic acids. The scope and limitations of this method have been examined.     

Synthesis of some analogues of (±)gelliusine F, (±)gelliusine E,and total synthesis of 2,2-di(6′-bromo-3′-indolyl)ethylamine

Synthesis of some analogues of indole based marine alkaloid (±)gelliusine F, (±)gelliusine E, and total synthesis of 2,2-di(6′-bromo-3′-indolyl)ethylamine are reported.     

Synthesis of Functionalized Dihydrofurocoumarin Derivatives from 3-Aminoalkyl-4-hydroxycoumarin

Some dihydrofuro-fused coumarin derivatives were synthesized from 3-aminoalkyl-4-hydroxycoumarin via in situ generation of N-ylide. The 3-aminoalkylated 4-hydroxycoumarin derivatives were synthesized from one-pot, three-component reaction of 4-hydroxycoumarin, aryl aldehydes, and secondary amines in ethanol at room temperature. Again, when salicylaldehyde was employed instead of benzaldehyde, interestingly pyranocoumarins were obtained. The reaction protocol can be further explored toward the synthesis of many other heterocyclic fused dihydrofurans.     

An efficient and regioselective one-pot multi-component synthesis of pyrimido[4,5-d]pyrimidine derivatives in water

Pyrimido[4,5-d]pyrimidine derivatives 4 have been prepared in an efficient and regioselective manner in water via multi-component reaction of isothiocyanate 1, aromatic aldehyde 2, N,N-dimethyl-6-amino uracil 3 in the presence of p-toluenesulfonic acid (p-TSA) as a Lewis acid catalyst.     

Metal‐Modified Nucleic Acids: Metal‐Mediated Base Pairs,Triples, and Tetrads

The incorporation of metal ions into nucleic acids by means of metal‐mediated base pairs represents a promising and prominent strategy for the site‐specific decoration of these self‐assembling supramolecules with metal‐based functionality. Over the past 20 years, numerous nucleoside surrogates have been introduced in this respect, broadening the metal scope by providing perfectly tailored metal‐binding sites. More recently, artificial nucleosides derived from natural purine or pyrimidine bases have moved into the focus of Ag^I‐mediated base pairing, due to their expected compatibility with regular Watson–Crick base pairs. This minireview summarizes these advances in metal‐mediated base pairing but also includes further recent progress in the field. Moreover, it addresses other aspects of metal‐modified nucleic acids, highlighting an expansion of the concept to metal‐mediated base triples (in triple helices and three‐way junctions) and metal‐mediated base tetrads (in quadruplexes). For all types of metal‐modified nucleic acids, proposed or accomplished applications are briefly mentioned, too.     

Basic alumina supported one-pot synthesis of structurally diverse pyridine/quinolinine-fused novel diazepanium, diazocanium, imidazodilinium and tetrahydro-pyrimidiniums

Basic alumina supported solvent-free one-pot synthesis of pyridine-fused polycyclic diazepaniums was achieved under microwave irradiation. The process was successfully extended to the synthesis of pyridine-fused bicyclic imidazolidiniums and tetrahydro-pyrimidiniums and also of tri- and tetracyclic diaza-heterocycle-fused quinoliniums. The dual characteristic of basic alumina, a solid support as well as a base, was successfully employed in the current investigation. The method emerged to be an effective route in terms of product yield, reaction time, and ease of purification and most importantly for environment friendly protocols.     

Synthesis of highly functionalized indeno[1,2-b]furans

Some novel functionalized indeno[1,2-b]furans were synthesized from the reaction of indandione/indanone and aldehydes at room temperature followed by the reaction of the Knoevenagel condendensed intermediate with 4-hydroxycoumarins in the presence of iodine as catalyst in dimethyl sulfoxide (DMSO) under thermal conditions. The reaction involved in a condensation and Michael addition followed by lactone ring opening and intramolecular cyclization process to afford the product in high yield in easy work-up procedure.     

Synthesis,characterization, electrochemical and theoretical study of substituted phenyl-terpyridine and pyridine-quinoline based mixed chelate ruthenium complexes

In the present work, we report two methoxy-substituted phenyl-terpyridine ruthenium complexes with pyridine carboxyquinoline and NCS as ancillary ligands, [Ru(OMePhtpy)(pcqH)(NCS)](PF₆) (1) and [Ru(triOMePhtpy)(pcqH)(NCS)](PF₆) (2) (where OMePhtpy = (4′-(4-methoxy)phenyl-2,2′:6′,2″-terpyridine, triOMePhtpy = (4′-(3,4,5-trimethoxy)phenyl-2,2′:6′,2″-terpyridine and pcqH = pyridine-carboxyquinoline). Both complexes have been characterized by spectroscopic techniques e.g., mass, ¹H-NMR and FTIR. UV–vis spectrophotometric and electrochemical studies for both complexes have been performed. The substitution pattern of the –OMe groups have been successfully utilized to tune the redox potential of the metal complexes. On the anodic side of cyclic voltammogram, 1 and 2 show an irreversible wave corresponding to Ru^II/III couple at 0.95 and 0.85 V, respectively. The lower Ru^II/III oxidation potential for 2 may be attributed to increased electron density on ruthenium due to three (+R) methoxy–groups appended to the phenyl moiety of triOMePhtpy. DFT optimization of structure and energy calculation reveals that in both complexes, HOMO is metal- and thiocyanate-based, whereas the LUMO is based on pcqH. Correlation of TDDFT results with experimental electronic spectrum indicates that bands at 502 nm (1) and 528 nm (2) are of MLLCT character from ruthenium-thiocyanate to pcqH.     

Montmorillonite K-10 clay catalyzed solvent-free synthesis of bis-indolylindane-1,3-dione, 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-dione and bisindolylindeno[1,2-b]quinoxaline under microwave irradiation

An environmentally benign protocol has been described for the synthesis of novel 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-diones/bis-indolylindane-1,3-diones from ninhydrin and 3-substituted/unsubstituted indoles. It uses montmorillonite K-10 as catalyst in a solvent-free condition under microwave irradiation. The method was also used for the synthesis of novel bisindolylindeno[1,2-b]quinoxaline derivatives.