Alkyl–alkenyl coupling reaction between unactivated alkyl iodides and 2-arylalkenylboronic acids utilizing
a Pd/light combined system was studied. This reaction provided 2-alkylarylalkenes in good yields. It is proposed
that in this reaction alkyl radicals are formed by SET from a Pd catalyst to alkyl iodides, which then
undergo addition reactions to form C–C double bonds of alkenyl boronic acids and the subsequent
β-fragmentation of boronyl radicals leads to the formation of alkyl-substituted arylalkenes.
Synthesis of Aliphatic Amides through a Photoredox Catalyzed Radical Carbonylation Involving Organosilicates as Alkyl Radical Precursors Cartier, Alex, Levernier, Etienne, Dhimane, Anne-Lise , Fukuyama, Takahide , Ollivier, Cyril, Ryu, Ilhyong, Fensterbankb, Louis Adv. Synth. Catal., 2020, 362, 10 pp. 2254 - 2259 DOI: 10.1002/adsc.202000314
Alkyl radicals, from primary to tertiary, formed by photocatalyzed oxidation of organosilicates, are involved efficiently in radical carbonylation with carbon monoxide (CO), in the presence of various amines and CCl4, leading to a variety of amides in moderate to good yields.
Syntheses of Diarylethenes by Perylene-catalyzed Photodesulfonylation from Ethenyl Sulfones Watanabe, Hikaru, Takemto, Mai, Adachi, Kazumasa, Okuda, Yasuhiro, Dakegata, Aki, Fukuyama, Takahide, Ryu, Ilhyong, Wakamatsu, Kan, Orita, Akihiro Chem. Lett., 2020, 49, 4 pp. 409 - 412 DOI: 10.1246/cl.200046
Diarylethenes were obtained from the corresponding ethenyl sulfones by photocatalyzed desulfonylation using UV or blue LEDs. When perylene and i-Pr2NEt were used as a photocatalyst and a sacrificing reagent, respectively, this desulfonylation proceeded smoothly to afford the desired ethenes with the functional groups such as chloro, alkoxy and heteroaromatic rings remaining untouched. The use of a flow photoreactor enabled this desulfonylation to proceed more rapidly to finish in an hour of residence time.
Site-Selective C(sp3)–H Functionalization of Fluorinated Alkanes Driven by Polar Effects Using a Tungstate Photocatalyst Fukuyama, Takahide, Nishikawa, Tomohiro, Ryu, Ilhyong Eur. J. Org. Chem., 2020, 2020, 10 pp. 1424 - 1428 DOI: 10.1002/ejoc.201901135
The TBADT‐catalyzed C(sp3)–H functionalization of perfluorophenyl‐ and perfluoroalkyl‐substituted alkanes was studied to determine how the fluorous substituents affect site‐selectivity. Alkylation of alkyl‐substituted perfluorobenzene avoids α‐C–H bonds, unlike their alkylbenzene counterparts, allowing site‐selective functionalization of C–H bonds remote to the aromatic ring. Alkylation of alkanes having a perfluoroalkyl group also avoided α‐C–H bonds. Radical polar effects in the SH2 transition states could explain this avoidance of α‐C–H functionalization.