Metal‐Free One‐Pot Conversion of Olefins and Alkynes to Amides Using TsNBr 2 , I 2 and Aqueous NH 3 at Room Temperature

Silver acetate-catalyzed synthesis of cyclic sulfonyl guanidine with exocyclic double bond

An efficient protocol for the synthesis of cyclic guanidine with exocyclic double bond has been developed. The synthesis has been achieved via intramolecular hydroamination of an intermediate propargyl guanidine by using silver acetate as catalyst in the presence of acetic acid. The reaction proceeds via the formation of acyclic propargyl guanidine in a one-pot reaction of N,N-dibromoarylsulfonamides, isonitriles, and propargylamine in the presence of K2CO3. In the second stage of the synthesis, the acyclic guanidine selectively undergoes 5-exo-dig cyclization in the presence of silver acetate and acetic acid to produce the five-membered cyclic guanidine framework having an exocyclic double bond as the constituent part. Short reaction time, wide substrate scope with good to high yields, and good functional group tolerance are the remarkable achievement of the present protocol.

Atmospheric Oxygen Facilitated Oxidative Amidation to α-Ketoamides and Unusual One Carbon Degradative Amidation to N-Alkyl Amides

A mild, transition-metal-free novel synthetic approach for the construction of C═O and C-N bonds has been demonstrated. Easily accessible gem-dibromoalkenes under similar conditions form oxidative amidation product α-ketoamides and unusual degradative amidation product N-alkyl amides by simply changing the amine substitute. Atmospheric air containing molecular oxygen proved to be an ideal oxidant for an amidation reaction. Under similar conditions, the electron-deficient gem-dibromoalkenes play a dual role with different formamides forming novel oxidative amidation products and by the state of art neighboring group participation of amine to unusual one-carbon degradative amidation products.

Unanticipated switch of reactivity of isonitrile via N≡C bond scission: Cascade formation of symmetrical sulfonyl guanidine

Unanticipated formation of symmetrical sulfonyl guanidine was observed while treating isonitriles with N,N-dibromoarylsulfonamides in absence of an external amine source. Interesting feature of this work is that one molecule of isonitrile initially reacts with dibromoarylsulfonamide via the C-end to produce the intermediate carbodiimide while the other molecule undergoes C≡N triple bond cleavage to react as amine source with the intermediate. This switch of reactivity from C-center to N-center of the isonitrile generated symmetrical guanidine.

Unprecedented 1,3-tert-butyl migration via the C–N single bond scission of isonitrile: an expedient metal-free route to N-sulfonyl amidines

Treatment of tert-butyl isonitrile with ArSO₂NBr₂ and nitrile led to simultaneous C–N single bond scission of isonitrile and migration of tert-alkyl group to nitrogen centre of the nitrile precursor, resulting in the formation of N-sufonyl amidine.