Current Organic Chemistry - Volume 20, Issue 20, 2016

The literature on the syntheses of substituted 1-(indol-3-yl)-1,2,3,4-tetrahydroisoquinoline derivatives is reviewed. Two main synthetic procedures have been applied for these syntheses. One is cross-dehydrogenative coupling, which can furnish various C-3 functionalized indoles; oxidants and/or catalysts are usually needed. Another convenient synthetic method is the aza-Friedel–Crafts alkylation of indole derivatives with dihydroisoquinoline, the main advantage of this being the direct catalyst-free coupling under mild experimental conditions. The review also considers miscellaneous reactions, where the isoquinoline skeleton is achieved in one of the final steps of the synthesis.

Graphene is an atomically thin, two-dimensional allotrope of carbon with excellent chemical, mechanical, and electronic properties. Recent studies have revealed that using graphene or modified graphene as a catalyst support or metal-free catalyst can result in significant improvement in the catalytic activity, selectivity, reusability and tolerance due to the unique structure of graphene. This review summarized the recent progress on the preparation of the graphene-based catalysts and their application in traditional chemical reactions, electrochemical reactions and photochemical catalysis. The perspectives of achieving graphene-based catalysts with high catalytic performance have also been included.

N,N-Dibromosulfonamides are unique reagents in organic synthesis and have been employed in several areas of application. They have demonstrated high reactivity in bromination reactions, vicinal bromoamine synthesis, in the construction of C-N bonds, and several other transformations. This review describes the scope and application of the N,Ndibromosulfonamides as bromine sources, as amine sources, as sources of both amine and bromine, as oxidation reagents, or as catalysts.

Phosphaalkenes and azaphospholes both have C=P- moiety; while the former is stabilized kinetically, the latter attains stability thermodynamically. A close examination of the synthesis, structures and reactivity of these two classes of phospha-organic compounds reveals that these compounds exhibit close analogy with their respective non-phospha analogues, namely alkenes and azoles. In this mini-review, the analogies between phosphaalkenes and alkenes on the one hand and between azaphospholes and azoles on the other hand have been explained and highlighted on the basis of some important examples of syntheses, structures and reactions in each case. Some of the reactions of these two classes of compounds which are not given by their carbon-analogues are attributable to a weaker carbonphosphorus π-bond and the presence of a lone pair on the phosphorus atom.

As the high-profile new environmental material, ionic liquid is widely used in various fields with its extraordinary performance. It can be used as a substitute of traditional functional material and it also provides a theoretical basis for research and development of new material. This paper introduced the applications of ionic liquid in physical, chemical and biological areas as lubricant, plasticizer, variable focus lenses, optical response material, optical monitoring CO2 sensor, anti-static agent, energy storage battery, thermal material, magnetic material, intelligent material, gas absorption material, catalyst, refrigerant, antibacterial agent and herbicide, respectively. The ionic liquid materials usually provided better properties than traditional functional materials with wider application conditions and amazing effects. It is noteworthy that the ionic liquid is a green material for its environmental characteristics and economic benefits. At last, the further expectations of ionic liquid applied in material fields were put forward.

The reaction of variously N-substituted α-furanamides with singlet oxygen has been examined. In addition to the expected fragmentation products the reaction affords rearranged 5-hydroxy- and 5-aryloxy-2(5H)-furanones. Products distribution depends on diverse factors: the presence of α-hydrogen, the presence of the amidic group, the nature and the number of nitrogen substituents. The rearrangement to 5-aryloxy-2(5H)-furanones is unreported.

An efficient, atom-economical, four-component one-pot reaction method was developed for pyrano[2,3-c]pyrazole-3-carboxylates using dimethylacetylenedicarboxylate, hydrazine hydrate, malononitrile and aromatic aldehydes, using a RuCaHAp catalyst. Ten new substituted pyrano[2,3-c]pyrazole-3-carboxylate derivatives (5a-k) were synthesized in good to excellent yields (88 to 97%), at room temperature with short reaction times (≈ 30 min) using the green solvent aqueous ethanol. RuCaHAp was prepared and characterized by various techniques including SEM, TEM, P-XRD and BET spectroscopy. The proposed heterogeneous catalyst that can be easily synthesized, is inexpensive and stable with good reusability (at least 6 times) showing marginal loss of activity. The suggested environmentally benign protocol offers high yields, clean reaction profiles, operational simplicity and no need for chromatographic separations.