N-Phenyl-1-aza-2-cyano-1, 3-butadienes: An intramolecular hetero Diels-Alder strategy for the construction of 1, 4-benzodiazepines

One-Pot Tandem Assembly of Amides, Amines, and Ketones: Synthesis of C4-Quaternary 3,4- and 1,4-Dihydroquinazolines

A multicomponent tandem assembly procedure for the synthesis of diverse C4-quaternary 3,4-dihydroquinazolines from amides, amines, and ketones has been developed. The one-pot reaction involves successive triflic anhydride mediated amide dehydration, ketimine addition, and Pictet-Spengler-like cyclization processes and affords products in up to 92% yield. Conversion of 3,4-dihydroquinazolines to the corresponding 1,4-dihydroquinazolines via a two-step N1 dealkylation and regioselective N3 functionalization protocol, including computational rationale for the observed regioselectivity, is also described.

Electron-deficient 1- and 2-azabuta-1,3-dienes: a comprehensive survey of their synthesis and reactivity

Electron-deficient 1- and 2-azabuta-1,3-dienes are reagents intrinsically able to provide a wide range of cyclic and acyclic N-containing building blocks. Depending on their substitution, they behave as dienes for Diels-Alder reactions, as partners for [4+1], [3+2], [2+2]-cycloadditions, for aziridinations and as electrophiles for 1,2 and 1,4-additions. Nowadays, they are a very versatile family of compounds, despite their usual instability and complex reactivity. Four decades of research in this challenging area are reviewed in this critical review: their synthetic aspects and their reactivity towards a wide range of dienophiles, dipoles and nucleophiles are described as well. The introduction focuses on their electronic properties in order to get a clear picture of their reactivity (190 references).