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An iodine‐catalyzed [3+2] cycloaddition/ring opening reaction of 1,1‐diacylcyclopropanes with sulfonyl hydrazides has been reported. In the presence of 20 mol‐% iodine, a range of structurally diverse fully substituted pyrazoles with a hydroxy functional group are obtained in moderate to excellent yields with extremely high regioselectivity. [ABSTRACT FROM AUTHOR]

Highly regioselective synthetic methodology leading to densely functionalised C(3), C(4) and C(5) substituted pyrazoles 10a–q, 14a‐i and 16a–g via thermal [3+2]‐dipolar cycloaddition, of α‐diazoacetates and α‐thio‐β‐chloroacrylamides, at the sulfide, sulfoxide and sulfone levels of oxidation, is described. This method allows access to C(4)‐sulfenyl or sulfonyl pyrazoles, through migration of the sulfur substituent at the sulfide and sulfone oxidation levels, while elimination of the sulfinyl group leading to 3,5‐disubstituted pyrazoles, is observed. While the sulfide migration is readily rationalised, the carbon to carbon 1,2‐sulfonyl migration is unprecedented and mechanistically intriguing. The synthetically versatile generation of densely functionalised pyrazoles containing substituents amenable to further modification offers advantages over alternative synthetic routes. Isolation of the N‐alkylated pyrazoles 11a and 12a as by‐products from the cycloaddition through further reaction of the pyrazoles 10 with excess α‐diazoacetate, proved useful in rationalising the tautomeric behaviour evident in the NMR spectra of the pyrazoles, with the position of tautomeric equilibrium influenced by solvent and substituents. [ABSTRACT FROM AUTHOR]

We developed a silver‐catalyzed strategy for the generation of sulfonyl radicals from sulfonamides derived from α‐amino acids. The reaction proceeded via a decarboxylation, N–S bond cleavage and radical cyclization sequence and allows the difunctionalization of alkynes and the synthesis of 3‐sulfonylated coumarins. The reaction tolerated a broad scope of substrates and functional groups and could be extended to the synthesis of oxindoles and an isoquinolinedione by the capturing of the sulfonyl radical with an alkene moiety. Moreover, the proposed mechanism was supported experimentally and by DFT calculations. A silver‐catalyzed sulfonylation strategy using sulfonamides derived from α‐amino acids is described. The reaction proceeded via decarboxylation, N–S bond cleavage and radical cyclization to provide a variety of coumarins. The reaction was suitable for the synthesis of 2‐oxindoles and an isoquinolinedione by the capturing of the sulfonyl radical with an alkene moiety and cyclization. [ABSTRACT FROM AUTHOR]

Mannich-type reactions of chiral δ-chloro- N- tert-butanesulfinyl-substituted imidates across N-sulfonyl aldimines resulted in the efficient and anti-stereoselective synthesis of new β-(sulfonylamino)- N-sulfinyl imidates ( dr > 99:1). These compounds were then successfully cyclized to give 2-aryl- N-sulfonylpiperidine-3-( N-sulfinyl)carbimidates in high yields. These proved to be useful intermediates for the synthesis of chiral methyl 2-arylpiperidine-3-carboxylates as well as cis-3-amino-2-aryl- N-sulfonylpiperidines. [ABSTRACT FROM AUTHOR]

The solid-phase synthesis of 4 H-benzo[ f][1,2,3]triazolo[1,5- a][1,4]diazepin-6(5 H)-ones and 4,5-dihydrobenzo[ f][1,2,3]triazolo[5,1- d][1,2,5]thiadiazepine 6,6-dioxides under mild and catalyst-free conditions is described. The seven-step synthetic strategy is based on the preparation of polymer-supported 4-nitrobenzenesulfonamides and their alkylation with various propargyl derivatives. Cleavage of the 4-nitrobenzenesulfonyl group from each of the key intermediates was followed by acylation with different 2-azidobenzoic acids, leading to spontaneous intramolecular (Huisgen) 1,3-dipolar cycloaddition. After cleavage from the polymer support, the target compounds were obtained in excellent crude purities and very good overall yields. [ABSTRACT FROM AUTHOR]