AIBN‐Initiated Denitrative Cross‐Coupling Reactions of β‐Nitrostyrenes with Sulfonyl Hydrazides/Disulfides: A Metal‐free Approach towards Vinyl Sulfones

Abstract

A practical approach involving denitrative coupling of β‐nitrostyrenes and sulfonyl hydrazides/disulfides by AIBN (azobisisobutyronitrile) has been developed to accomplish the synthesis of vinyl sulfones. The method employs easily accessible starting materials, and is endowed with a broad substrate scope and functional group tolerance.

Sulfonyl Hydrazides in Organic Synthesis: A Review of Recent Studies

“…β ‐nitrostyrenes could also be elegantly used in the preparation of vinyl sulfones via radical addition and denitration. The Singh and Peddinti group all reported the TBHP‐based oxidative system catalyzed reactions of β ‐nitrostyrenes without the utilization of additional metal catalyst. The Singh's method were effective for both electron‐deficient and electron‐rich substituents on the aryl moiety of the β ‐nitrosyrenes.…”

“…The Singh and Peddinti group all reported the TBHP‐based oxidative system catalyzed reactions of β ‐nitrostyrenes without the utilization of additional metal catalyst. The Singh's method were effective for both electron‐deficient and electron‐rich substituents on the aryl moiety of the β ‐nitrosyrenes. Electron‐deficient substituents did not favor the denitration in Peddinti's condition and hydrosulfonylation product was isolated instead (Scheme ).…”

Oxidative Sulfonylation of Multiple Carbon‐Carbon bonds with Sulfonyl Hydrazides, Sulfinic Acids and their Salts

“…β-Nitrostyrenes 240 containing both electron-donating and electron-withdrawing substituents in the aromatic ring as well as 1-(2-furyl)and 1-(2-thienyl)-2-nitroethylene, aromatic and aliphatic sulfonyl hydrazides 241 successfully entered this process (Scheme 110). [137] Vinyl sulfones 245 were also obtained from βnitrostyrenes 243 and sulfonyl hydrazides 244 under the action of the I 2 /TBHP system without solvent at room temperature. Interestingly, the addition of morpholine to the reaction mixture delivered α-sulfonylation products 246 as a result of sulfonyl moiety addition to the starting β-nitrostyrenes 243 (Scheme 111).…”

Denitrative Cross-Couplings of Nitrostyrenes

“…Although each proposal differs in detail, the main three characteristic steps feature in all proposals. Firstly, carbon- or heteroatom-centered radical 4 is generated in situ by various methods from precursors 6 – 33 [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ]. These include a thermal homolytic cleavage of labile bonds, metal-catalyzed and photochemically initiated processes.…”

“…A series of alternative cross-coupling partners for the preparation of conjugated sulfones from nitrostyrene was described in 2018 by Peddinti and Singh, respectively ( Scheme 21 and Scheme 22 ) [ 42 , 43 ]. Firstly, Peddinti described a rapid coupling of nitrostyrenes 1 with aryl sulfonyl hydrazides 24 , promoted by iodine and TBHP ( Scheme 21 , method A) [ 42 ].…”