Electrophilic cyclization of N-alkenylamides using a chloramine-T/I2 system

Nonactivated Aziridine Synthesis by Intermolecular Polarity-Mismatched Carboamination of Unactivated Alkenes with Unactivated Alkyl Halides

A general intermolecular polarity-mismatched carboamination reaction of unactivated alkenes with unactivated alkyl halides has been developed. A series of nonactivated alkyl-substituted aziridines were constructed in exclusive regioselectivity. The dual polarity-mismatched mechanism might be involved.

Direct Regioselective Reductive Allylation of Imines: Application to Synthesis of Oxazines with Halogenated Reagent

Oxazines are an important class of compounds in oxazine ligands and medical chemistry. Here, we describe a linear-selective allylation of imines with allyl electrophiles via cross-electrophile coupling reactions, followed by cyclization with halogenated reagents, providing a new strategy to afford oxazine compounds with a tetrasubstituted carbon center. Mechanistic studies indicate that α-amino carbanion, generated by successive single-electron transfer processes, is a key intermediate for nucleophile attack on π-allylpalladium in photoredox/palladium catalysis.

Halogen-Induced Controllable Cyclizations as Diverse Heterocycle Synthetic Strategy

In organic synthesis, due to their high electrophilicity and leaving group properties, halogens play pivotal roles in the activation and structural derivations of organic compounds. Recently, cyclizations induced by halogen groups that allow the production of diverse targets and the structural reorganization of organic molecules have attracted significant attention from synthetic chemists. Electrophilic halogen atoms activate unsaturated and saturated hydrocarbon moieties by generating halonium intermediates, followed by the attack of carbon-containing, nitrogen-containing, oxygen-containing, and sulfur-containing nucleophiles to give highly functionalized carbocycles and heterocycles. New transformations of halogenated organic molecules that can control the formation and stereoselectivity of the products, according to the difference in the size and number of halogen atoms, have recently been discovered. These unique cyclizations may possibly be used as efficient synthetic strategies with future advances. In this review, innovative reactions controlled by halogen groups are discussed as a new concept in the field of organic synthesis.

Synthesis of 3-Iodomethyl Sultams

A method for the synthesis of iodomethyl-substituted five-membered sultams has been developed. The sultams were synthesized by intramolecular iodoamination of alkenyl sulfamides. The method allows synthesis of N- and C-substituted sultams. NH-Sultams were prepared by acidic cleavage of the corresponding tert-butyl sultams that are readily available. Varying the length of alkenyl substituent at sulfamide it was shown that only five- and six-membered sultams could be prepared by this method. Neither four- nor seven-membered sultams were detected. The simple practical procedure and available starting materials make the variously substituted sultams readily available.

Benzene construction via Pd-catalyzed cyclization of 2,7-alkadiynylic carbonates in the presence of alkynes

A palladium-catalyzed highly regio- and chemo-selective cyclization of 2,7-alkadiynylic carbonates with functionalized alkynes to construct 1,3-dihydroisobenzofuran and isoindoline derivatives under mild conditions has been developed. Functional groups such as alcohol, sulfonamide, and indoles could be well tolerated. After careful mechanistic studies, a mechanism involving oxidative addition and regioselectivity-defined double alkyne insertions has been proposed.

A metal-free tandem ring-opening/ring-closing strategy for the heterocyclic conversion of benzoxazin-4-ones to oxazolines

A facile metal-free tandem ring-opening/ring-closing strategy was developed for the synthesis of oxazolines in good to excellent reaction yields under mild reaction conditions.