We report the unexpected formation of a 1-azadiene dimer from 4,6-diphenyl-3,6-dihydro-2H-1,3-thiazine-2-thiones under prolonged microwave irradiation. In this manner, thiazine-2-thiones act as "masked" 1-azadiene equivalents, which makes them useful synthetic tools to access complex heterocyclic frameworks. We compare this dimerization with earlier approaches and elaborate on the observed dias...

Diastereo- and enantioselective N-heterocyclic carbene catalyzed 1-azadiene Diels-Alder reactions of (E)-2-styrylbenzothiazoles with α-chloro aldehydes are reported. This annulation strategy provides an efficient access to medicinally important dihydrobenzothiazolopyridin-1-ones in good to excellent yields (44-97%) with very good to excellent stereoselectivities (up to 9:1 dr, 98% ee) and toler...

An efficient one-pot synthesis of anthraquinones and tetracenediones was achieved via L-proline catalyzed [4+2] cycloaddition of in situ generated azadiene from α,β-unsaturated aldehydes and 1,4-naphthoquinones or 1,4-anthracenedione in good to excellent yield. This protocol constitutes an unprecedented tandem benzannulation that allows one-pot construction of diverse anthraquinones and tetrace...

An indole-azadiene conjugate (1), synthesized by facile one-step condensation, behaves as a highly selective probe for detection of fluoride ion both in colorimetric and fluorometric analyses. The probe 1 shows F(-)-selective color change from colorless to yellow and appearance of green fluorescence. 1H NMR analysis and ab initio calculation reveal that the F(-)-induced colorimetric and fluorom...

The preparation and reactivity of 4-amino-1 -azadienes and electronically neutral 2-azadienes is reported. The suitability of the 1 -azadiene system for the synthesis of five-, six-, seven-, and eight-membered as well as the synthetic utility of 2-azadienes through [4+2] cycloadditions is presented. For some years the azadiene derivatives have attracted our attention due to their utility as syn...

A new bispyrenyl azadiene derivative has been synthesized and examined for its cation recognition abilities toward different cations. The ligand shows strong affinity for Hg(2+) ions over other cations such as Cu(2+), Pb(2+), Zn(2+), Ni(2+), Cd(2+), Ag(+), K(+), Na(+) and Li(+). An "Off-On" type of fluorescent behaviour was observed with simultaneous presence of Cu(2+) and Hg(2+) ions. An ion s...

A new intramolecular Lewis acid catalyzed hetero-Diels-Alder reaction of N-arylimines 5 with nonactivated olefins tethered to the 2-azadiene system was developed in order to prepare 1,2,3,4,4a,9,9a,lO-octahydroacridine derivatives 6. Both reactivity and cis/ trans selectivity of 6 were mainly dependent on the substitution pattern in the 3-position of the cyclization precursor 5. The type of Lew...