Iodine-Promoted Radical Cyclization in Water: A Selective Reaction of 1,6-Enynes with Sulfonyl Hydrazides

Abstract

An iodine-promoted one-pot radical cyclization reaction of 1,6-enynes with sulfonyl hydrazides to provide five-membered and hexatomic ring sulfonylated products under the same conditions is established. This reaction proceeded smoothly in water and gave the corresponding products by using I2/TBHP instead of expensive and toxic catalysts with C-S and C-I bond formed in one step. This method also allowed easy access to significant functional sulfones for potential applications in medicinal and organic chemistry.

Sulfonyl Hydrazides in Organic Synthesis: A Review of Recent Studies

“…The cyclization strategy with diverse unsaturated compounds is depicted in Scheme . Adduct intermediates triggered intramolecular cyclizations by the structure of arenes, alkenes, alkynes, or nitriles (Eq. 26‐1).…”

“…In our opinion, a summary classified by crucial intermediates will do much to help the application of diverse methodologies. As shown in Scheme , our review is based on ten categories: (1) sulfonyl radiacls; (2) thiosulfonates; (3) ArS . radicals; (4) sulfur‐centered anions; (5/6) metallo‐organic compounds with or without sulfonyl moiety; (7/8) electrophilic RSX or RS‐DBU intermediates; (9) nucleophilic hydrazines; (10) sulfonyl hydrazides as diazene or sulfinic acid surrogate.…”

RhI‐Catalyzed Cyclizative Addition Reaction of 1,6‐Enyne and Sulfonyl Chloride by Carbophilic Activation

“…However, radicalt esting disclosed that either TEMPO (2.5 equiv) or BHT (2.5 equiv) had little effect on the reaction of 10 with Ts Cl, which strongly excluded the pathway relevant to ar adical process. [10] On the basis of these results andour previous studies, aproposed mechanism is given in Scheme 2. The reaction begins from the generation of [(dppf)RhCl 2 Ts ]b yo xidative addition of Ts Cl to Rh I catalyst.…”

“…For the cases of enynes 1j-n with a1 -aryl alkene, excellent diastereoselectivity is still obtained. On the other hand, the yield varies with the electronic character( entries [10][11][12][13][14]. The presence of an electronrich aryl group, such as 4-MeO-C 6 H 4 and 4-Me-C 6 H 4 ,i sb eneficial for the isolationo fp roducts in high yields (entries10a nd 11).…”

Atom-Economic Synthesis of 4-Pyrones from Diynones and Water

“…Generally, water offers several "green chemistry" benefits as a solvent in organic transformations, including high efficiency, lower cost, ease of process, green and environmental protection [3,4]. Recently, there are many reports of clean transformations in water medium [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], such as coupling reactions [20][21][22][23][24][25][26][27][28][29][30], cyclizations [31][32][33][34], Michael additions [35][36][37][38][39], and condensations [40,41]. Additionally, H2O also participates in organic reactions as a nucleophile [42,43] to provide various kinds of functional compounds such as imidazo [1,2-a]pyridines [44], amino acid salts [45], α-amino ketones [46], and 1,3-oxazinan-2-ones [47]…”