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Imidazolidin-2-one and 1,3-benzodiazepin-2-one scaffolds are structural motifs of many biologically active compounds. Herein, we report a highly regioselective acid-catalyzed intramolecular nucleophilic cyclization/intermolecular electrophilic substitution reaction sequence of (2,2-dialkoxyethyl)ureas. The reaction benefits from readily available starting materials, a simple workup procedure, moderate to high yields of target compounds, and provides a convenient entry to previously unknown 4-(het)arylimidazolidinones and 5-(het)arylbenzodiazepinones. The proposed mechanism of the reaction is also discussed. [ABSTRACT FROM AUTHOR]

Organophosphorus pyrrolidine derivatives possessing P–N bonds are a promising yet underexplored class of compounds. In this short review we overview the general approaches to these compounds described so far, with a special emphasis on their asymmetric synthesis. 1 Introduction 2 Synthesis of Pyrrolidine-Based P(III) Derivatives 3 Synthesis of Pyrrolidine-Based P(V) Derivatives 3.1 Phosphorylation of Pyrrolidines with P(V) Acid Chlorides 3.2 Phosphorylation of Pyrrolidines with P(V) Acid Esters 3.3 Syntheses via the Atherton–Todd Reaction 3.4 Oxidation of Pyrrolidine-Based P(III) Derivatives 4 Syntheses of N -Phosphorylpyrrolidines from Acyclic Precursors 5 Conclusions [ABSTRACT FROM AUTHOR]

Pyrrolidine-based phosphonates, analogues of the natural amino acid proline, possess a diverse set of biological activity. The goal of this short review is to summarize the major developments in the synthesis of phosphaproline derivatives reported since 2004 with special emphasis on the mechanisms and limitations of the methods presented. 1 Introduction 2 Phosphorylation of Pyrrolidine Derivatives 2.1 Syntheses via Pudovik Reaction 2.2 Syntheses via Arbuzov Reaction 2.3 Decarboxylative Phosphorylation of Proline 2.4 Direct C–H Bond Phosphorylation 2.5 Other Reactions 2.6 Overview of Phosphorylation Methods 3 Synthesis of 2-Phosphorylpyrrolidines from Acyclic Precursors 3.1 Cyclization of 4-Substituted Butylamine Derivatives 3.2 [3+2]-Dipolar Cycloaddition of α-Iminophosphonates 3.3 Cyclization of Aminoalkynes and 4-Aminocarbonyl Compounds 4 Conclusions [ABSTRACT FROM AUTHOR]

The rare example of pyrrolidine C-N bond cleavage in 1-sulfonylpyrrolidines in acidic media in the presence of phenols is reported. The reaction proceeds under mild conditions and provides a convenient route to otherwise hardly accessible and previously unknown dibenzoxanthenes, diarylbutanes, and resorcinarenes having a sulfonylamide moiety. [ABSTRACT FROM AUTHOR]