Recent Advances in the Friedländer Reaction

Synthetic aspects of diels-alder cycloadditions with heterodienophiles

Publisher Summary This chapter reviews the chemistry of hydantoins. The hydantoins can be synthesized using amino acids, cyanate or thiocyanate salts, alkyl or aryl isocyanates and isothiocyanates, ureas, α-dicarbonyl compounds, Bucherer–Bergs and Read reactions, and cycloaddition reactions with heterocumulenes. The chapter also illustrates physicochemical studies on hydantoins. H-NMR, IR, and UV techniques are widely used to study ionization and tautomerism in hydantoins. Hydantoins are weak acids which owe their acidic character to dissociation of the proton bonded to the 3-nitrogen atom as this allows for maximum delocalization of charge in anion. The chapter also presents physicochemical studies on hydantoins using ultraviolet spectroscopy, mass spectrometry, infrared spectroscopy, nuclear magnetic resonance spectroscopy, crystal structure determinations, and quantum mechanical calculations. The reactivity of hydantoins and their derivatives are described further in the chapter. Hydantoins and thiohydantoins can react with nucleophilic and electrophilic as well as with other types of reagents. On protonation in a strongly acidic solution, hydantoin cations are formed. Hydantoins can easily be alkylated in the N-3 position by treatment with alkyl halides in an alkaline solution in protic or aprotic solvents. Other alkylating agents include dimethyl sulfate and diazomethane.

The Chemistry of Hydantoins

The total synthesis of streptonigrin and related antitumor antibiotic natural products

A metal-free, visible light-induced [4+2] benzannulation of biaryldiazonium salts with alkynes was developed. With eosin Y as photoredox catalyst, a variety of 9-substituted or 9,10-disubstituted phenanthrenes were obtained via a cascade radical addition and cyclization sequence.

Phenanthrene Synthesis by Eosin Y‐Catalyzed, Visible Light‐ Induced [4+2] Benzannulation of Biaryldiazonium Salts with Alkynes

Quinolizidine alkaloid synthesis via the intramolecular imino Diels-Alder reaction. epi-Lupinine and cryptopleurine

Total Synthesis of the Antitumor Antibiotic Streptonigrin

Alkaloid synthesis by the intramolecular imino Diels-Alder reaction. .delta.-Coniceine and tylophorine

A direct conversion of esters to nitriles

Alkaloid synthesis by the intramolecular imino diels-alder reaction. δ-coniceine and tylophorine

Nazir A. Khatri

Papers

Quinolizidine alkaloid synthesis via the intramolecular imino Diels-Alder reaction. epi-Lupinine and cryptopleurine

Total Synthesis of the Antitumor Antibiotic Streptonigrin

Alkaloid synthesis by the intramolecular imino Diels-Alder reaction. .delta.-Coniceine and tylophorine

A direct conversion of esters to nitriles

Alkaloid synthesis by the intramolecular imino diels-alder reaction. δ-coniceine and tylophorine