Time and Atom Economical Regio‐ and Chemoselective Radical Cyclization of Unactivated 1,6‐Enynes Under Metal‐ and Oxidant‐Free Conditions

Abstract

We developed time-atom economic regio-and chemoselective sulfonyl radical triggered 5-exo-dig cyclization of unactivated 1,6-enynes with sulfonyl halides under metal, additive-free reaction conditions to achieve highly substituted five-membered heterocyclic compounds. This transformation creates three new bonds, such as CÀ SO 2 , CÀ C, and active CÀ I/ Br bonds. Importantly, one-pot protocols produce desired products directly from sodium sulfinates and have an additional advantage such as minimising chemical waste, saving time, and simplifying practical aspects compared to existing protocols.

Photocatalytic Cross‐Pinacol Coupling Promoted by Carbon Dioxide**

“…Additional references cited within the Supporting Information. [22][23][24][25][26][27][28][29][30][31][32]…”

Photocatalytic 1,4-Addition of Aromatic Aldehydes or Ketones via Umpoled Carbinol Anions

“…The reaction mixture was stirred for 36 hours under blue light irradiation (100% light intensity from 40 W Kessil A160WE Tuna Blue; max = 462 nm. 7 The vial was placed 2 cm away from the LED light with a fan to keep the reaction temperature at room temperature). Water was added and the resulting mixture was extracted with AcOEt (three times).…”

“…4c However, carbinol radicals 6 are not fully compatible with the photocatalytic Giese-type 1,4-addition reaction and often dimerize to form vicinal 1,2-diols (i.e., they undergo pinacol coupling) (Scheme 2). [7][8][9] Indeed, to the best of our knowledge, well-developed research on the photocatalytic intermolecular Giese reaction of carbinol radicals has been limited to the recent pioneering reports of the groups of He and Guan, 10 and Lin. 11 We had good reason to believe that our findings on the photocatalytic generation of carbinol anions through a two-electron reduction of carbonyl substrates should realize an ionic 1,4-addition of carbinols, offering a good alternative to the ketyl Giese reaction.…”

Visible-Light-Enabled Ph3P/LiI-Promoted Tandem Radical Trifluoromethylation/Cyclization/Iodination of 1,6-Enynes with Togni’s Reagent

“…Similar reaction methods are mostly realized with transition-metal or hypervalent iodine reagents . Moreover, as important radical acceptors and synthetic intermediates, 1, n -enynes ( n = 5, 6, 7) could accept the addition of different radicals, such as carbon-centered radicals (including CF 3 radicals, difluoroalkyl radicals, aldehyde radicals, and aryl radicals) and nitrogen-centered radicals, to afford useful functional-group-containing and highly functionalized five- and six-membered heterocyclic products via the ATRC process. − In 2014, Liang and co-workers envisioned a strategy for cyanotrifluoromethylation with concomitant carbocyclization of 1,6-enynes using TMSCN to afford nitrile products (Scheme a) . At the same time, Liu and co-workers applied this reagent to the radical cascade cyclization of 1,6-enynes using iodine pentoxide (I 2 O 5 ) as a SET oxidant.…”