Selective S-arylation of 2-oxazolidinethiones and selective N-arylation of 2-benzoxazolinones/2-benzimidazolinones.

There exist three possible patterns for the reaction of cyclic 2-oxazolidinethione and 2-benzoxazolidinethione with arynes, namely (a) S-arylation, (b) N-arylation, and (c) aryne insertion into the thiocarbonyl group (C[double bond, length as m-dash]S). Our studies demonstrate that S-arylation wins out affording S-aryl dihydrooxazoles. In contrast, for related reactions of cyclic 2-benzoxazolinone and 2-benzimidazolinone with arynes, it is found that N-arylation outcompetes O-arylation and aryne insertion into the C[double bond, length as m-dash]O group to give N-aryl 2-benzoxazolinones and N-aryl 2-benzimidazolinones.

Facile synthesis of aza-spirocyclopropanyl oxindoles by the reaction of 3-(2-bromoethyl)-indole with 2,3-dimethylimidazole-1-sulfonyl azide triflate.

3-(2-Bromoethyl)indole reacts with 2,3-dimethylimidazole-1-sulfonyl azide triflate to give an intermediate N-(2,3-dimethylimidazole)-1-sulfonyl aza-spirocyclopropanyloxindole. This reactive species is captured by an alcohol or amine to afford the corresponding aza-spirooxindole sulfonate and sulfonamide.

Intramolecular Schmidt Reaction of Vinyl Azides with Cyclic Ketones.

Cyclic ketones tethered with a vinyl azide group undergo a Schmidt-hydrolysis sequence to give secondary lactams bearing a ketone side chain. Secondary lactams are obtained in a regioselective manner that is not possible in a conventional Schimdt reaction. In addition to the well-documented C-2 nucleophilicity, the N nucleophilicity of vinyl azide disclosed in this work opens a new direction for reaction invention involving vinyl azides.

Stereoselective Construction of Bridged trans-aza-Bicyclo[7/6,3/2,1]alkenyl Imines through Ring Expansion aza-Cope Rearrangement.

A highly stereoselective method for efficient synthesis of unprecedented bridged bicyclo[7/6,3/2,1]alkenyl amidines is described using cyclic N-allyl-aminoalkyne as a substrate. A ketenimine formation/cyclization/aza-Cope rearrangement cascade proceeds either with or without the aid of external DIPEA depending on substrate basicity. Fused bicycloamidines are also obtained via the same protocol using different N-allyl cyclic aminoalkynes.

The Reaction of 2,3-Dimethylimidazole-1-sulfonyl Azide Triflate with 3-Substituted Indoles: Reactivity and Scope.

2,3-Dimethylimidazole-1-sulfonyl azide triflate reacts with 3-substituted indoles to deliver 2-iminoindolines, 2-aminoindoles, or 2-imino-3-aminoindolines by using different conditions. This imidazolium sulfonyl azide shows higher reactivity toward carbon nucleophile indoles than ordinary alkyl/aryl sulfonyl azides.