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 (CS). 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 CO group to give N-aryl 2-benzoxazolinones and N-aryl 2-benzimidazolinones.

An intramolecular ketene aza-Claisen rearrangement is developed for the first time to enable the stereoselective synthesis of α-ally-α-cyano-lactams from N-allyl amino esters. This reaction also exhibits outstanding chemoselectivity when an unsymmetrical bis-N-allyl group is present in the starting molecule. The usefulness of this method is demonstrated by a short synthesis of optically active bicyclolactam from l-proline.

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.

•Chemo-, regio-, and stereoselective hydroboration of 1,3-enyne alcohol/amine is achieved.•Catalyst combination of CuCl/PCy3/NaOtBu provides the optimized outcomes.•The alkene configuration of starting enyne is conserved.•Aromatic substitution changes the regioselectivity.Hydroboration of conjugated enyne alcohol/amine is studied by using copper salts and bis(pinacolato)diboron as pre-catalysts and boron source respectively. It is suggested that the chemo-selectivity is derived from a combined electronic influence of the heteroatoms on the substrate and the ligand on the transition metal. The regioselectivity is probably dominated mainly by electronic effect of the alkyne substituent. This study resulted in a highly selective protocol to access Z,Z-/Z,E-1,3-dien-1/2-ylboronic ester bearing hydroxyl/amino group.Chemo-, regio-, and stereoselective hydroboration of conjugated enyne alcohol/amine has been realized through catalyst combination-CuCl/PCy3/NaOtBu, providing facile access to Z,Z- or Z,E-1,3-dien-1/2-ylboronate bearing hydroxyl/amino groups.

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.

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.

A copper(II) acetate catalyzed ring-opening cross-coupling of cyclopropanol with sulfonyl azide has been developed. By this method, various β-amino ketones have been made efficiently in medium to high yields and venerable functional groups such as benzylic C–H, alkyl and aryl bromides, alkyl sulfonate, silyl ether and alkene are compatible with these reaction conditions. Control experiments have precluded the involvement of both radical and simple copper nitrene intermediates and a possible mechanism featuring key steps of ring-opening metalation and alkyl group migratory insertion into copper nitrene has been proposed.

A one-pot synthesis of N-alkyl acridone via rhodium catalyzed decomposition of N-phenyl-2-(1-sulfonyl-1H-1,2,3-triazol-4-yl)aniline and subsequent oxidative C–C bond fragmentation has been developed. 14 examples are presented and the yields range from 30% to 80%.

An efficient and convenient protocol has been developed for ether bond formation in mild conditions. A mixture of primary/secondary ester and allylic/benzylic halide in tetrahydrofuran was treated with KOtBu at room temperature to give ether in high yield. This step economic method enabled direct alkylation of the acyl group masked O-nucleophiles. Application of this method in carbohydrate synthesis was feasible and chemo-selectivity can be achieved.

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 (CS). 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 CO group to give N-aryl 2-benzoxazolinones and N-aryl 2-benzimidazolinones.

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.