Controllable chemoselectivity in the coupling of bromoalkynes with alcohols under visible-light irradiation without additives: synthesis of propargyl alcohols and α-ketoesters

Abstract

The chemoselectivity of visible-light-induced coupling reactions of bromoalkynes with alcohols can be controlled by simple changes to the reaction atmosphere.

Nature of the Nucleophilic Oxygenation Reagent Is Key to Acid-Free Gold-Catalyzed Conversion of Terminal and Internal Alkynes to 1,2-Dicarbonyls

“…55 Brown solid (40.7 mg, 94%), R f 0.30 (hexane/ethyl acetate 8:1); 1 H NMR (400 MHz, CDCl 3 ) δ 8.04 (d, J = 7.2 Hz, 2H), 7.82 (dd, J = 12.0, 4.4 Hz, 2H), 7.66 (t, J = 7.4 Hz, 1H), 7.51 (t, J = 7.8 Hz, 2H), 7.18 (dd, J = 4.7, 4.1 Hz, 1H); 13 N-Methyl-2-oxo-2-phenyl-N-tosylacetamide (12r). 91 White solid (49 mg, 94%), R f 0.30 (hexane/ethyl acetate 4:1); 1 H NMR (400 MHz, CDCl 3 ) δ 7.95 (d, J = 7.1 Hz, 2H), 7.89 (d, J = 8.4 Hz, 2H), 7.64 (t, J = 7.4 Hz, 1H), 7.53 (t, J = 7.6 Hz, 2H), 7.39 (d, J = 8.0 Hz, 2H), 3.24 (s, 3H), 2.46 (s, 3H); 13 92 Yellow oil (31.2 mg, 95%); R f 0.50 (hexane/ethyl acetate 4:1); 1 H NMR (400 MHz, CDCl 3 ) δ 8.02 (d, J = 7.1 Hz, 2H), 7.66 (t, J = 7.5 Hz, 1H), 7.52 (t, J = 7.9 Hz, 2H), 3.98 (s, 3H); 13 1-Phenylpropane-1,2-dione (14a) 94 and 1-Phenylprop-2-en-1one (15a). 95 Yellow oil (17.5 3,3-Dimethyl-1-phenylbutane-1,2-dione (14b) 96 and 2,3-Dimethyl-1-phenylbut-2-en-1-one (15b).…”

Copper(I)-Catalyzed Aerobic Oxidation of α-Diazoesters

“…The solvent was removed by rotary evaporation and purified by silica gel column chromatography with petroether/ethyl acetate (50:1) as the eluent to give the desired products 2a – 2n . Compounds 2a – 2c , 2d , 2e , 2f , 2g , 2h – 2i , 2j – 2k , 2l , 2m , 2n , ( Z )- 3 , ( Z )- 4 , and ( E )- 4 are known.…”

Multicomponent Assembly of α,α‐Bis‐Sulfonyl Arylketones and Multiple Substituted Conjugated Dienes Induced by Visible‐Light Irradiation without Additives and Photocatalysts

“…[11] Recently, our group reported a photoinduced oxidative amidation of bromoalkynes with anilines and a controllable chemoselectivity in coupling bromoalkynes with alcohols, in which the corresponding products of α-ketoamides, propargyl alcohols and α-ketoesters were generated without use of additional reagents (e. g. catalysts, oxidants and other additives). [12] This reaction mode appears to be more effective and practical than many reported photoredox reactions. Furthermore, we discovered other novel visible-light-initiated transformations of bromoalkynes using sulfinic acids as substrates.…”