Regiospecific synthesis of neuroprotective 1,4-benzoxazine derivatives through a tandem oxidation–Diels–Alder reaction

Highly functionalized 1,4-benzoxazine derivatives have been synthesized at room temperature, with complete regiochemical control, through a tandem oxidation–Diels–Alder reaction.

Progress of the synthesis of condensed pyrazole derivatives (from 2010 to mid-2013)

Condensed pyrazole derivatives are important heterocyclic compounds due to their excellent biological activities and have been widely applied in pharmaceutical and agromedical fields. In recent years, numerous condensed pyrazole derivatives have been synthesized and advanced to clinic studies with various biological activities. In this review, we summarized the reported synthesis methods of condensed pyrazole derivatives from 2010 until now. All compounds are divided into three parts according to the rings connected to pyrazole-ring, i.e. [5, 5], [5,F 6], and [5, 7]-condensed pyrazole derivatives. The biological activities and applications in pharmaceutical fields are briefly introduced to offer an orientation for the design and synthesis of condensed pyrazole derivatives with good biological activities.

Environmentally Benign Lewis Acid Promoted [2+3]-Dipolar Cycloaddition Reactions of Nitrile Imines with Alkenes in Water

Mild and environmentally benign Lewis acid promoted 1,3-dipolar cycloaddition reactions of α-hydrazonyl chlorides with alkenes in water are reported. These α-hydrazonyl chlorides, in the presence of Lewis acids, generate nitrile imines in situ which react with dipolarophiles to furnish the corresponding cycloaddition products. In many cases, the required times for the completion of the Lewis acid promoted 1,3-dipolar cycloaddition reactions in water were comparable to the equivalent reactions performed in an organic solvent. Analogous tetrahexylammonium chloride promoted 1,3-dipolar cycloaddition reactions were also performed. The comparison of reaction times and cycloadduct yields for the aforementioned 1,3-dipolar reactions in aqueous and organic media as well as the proposed role of the Lewis acid in the 1,3-dipolar cycloaddition reaction are described.