Synthesis of a new series of 2-vinylindoles and their cycloaddition reactivity

Fused Polycyclic Compounds via Cycloaddition of 4-(1′-Cyclohexenyl)-5-iodo-1,2,3-triazoles with 4-Phenyl-1,2,4-triazoline-3,5-dione: The Importance of a Sacrificial Iodide Leaving Group

“…The observation of the solvent adducts 1B and 1C in diastereomeric mixtures leads to the formulation of a stepwise mechanism involving a polar intermediate ( PI in Scheme ). The electrophilic addition of PTAD to an alkene, a diene, or an arene may involve a zwitterionic intermediate. − As proposed in Scheme , following the addition of PTAD to 1T , the zwitterionic intermediate PI containing a benzylic-like cation may undergo proton transfer (paths A and A′) to afford enamide 1A and major product 1 , or solvolysis to give 1B or 1C in a mixture of diastereomers. In addition to these pathways, the PI may choose ring closure to give the formal Diels–Alder product 1D , which tautomerizes to the major ene reaction product 1 or undergoes stereospecific S N 2′ solvolysis due to the propensity of the urazolyl as a leaving group to give 1B or 1C as single diastereomers.…”

DDQ-Mediated Oxidative Coupling: An Approach to 2,3-Dicyanofuran (Thiophene)

“…With this in mind, we initially used a challenging tetralone 5a as a substrate under the described optimal conditions. This substrate could also form an enone via a well-known DDQ-mediated dehydrogenation. ,, No reaction occurred upon treatment of 5a with DDQ at room temperature in CH 3 CN. To our delight, treatment of 5a with DDQ under reflux successfully delivered the corresponding 2,3-dicyanofuran 6a , instead of a dehydrogenation product, in 61% yield and accompanied by 10% of 6aa , an oxidative aromatization product from 6a .…”