A greener process for flow C–H chlorination of cyclic alkanes using in situ generation and on-site consumption of chlorine gas Takahide Fukuyama, Masashi Tokizane, Akihiro Matsui, Ilhyong Ryu React. Chem. Eng., 2016, 1, pp. 613 - 615 DOI: 10.1039/C6RE00159A
Photo-chlorination of C–H bonds was investigated by using a photo microreactor and gaseous chlorine in situ generated from HCl and NaOCl. Under photoirradiation using a black light (15 W, 352 nm), chlorination of hydrocarbons proceeded smoothly within 1 min residence time to give chlorinated products in good yields.
Synthesis of 2,3-disubstituted indenones by cobalt-catalyzed [3+2] annulation of o-methoxycarbonylphenylboronic acid with alkynes Mitsuhiro Ueda, Tamami Ueno, Yuki Suyama, Ilhyong Ryu Chem. Commun., 2016, 52, 90 pp. 13237 - 13240 DOI: 10.1039/C6CC08032D
Treatment of alkynes with o-methoxycarbonylphenylboronic acid in the presence of a cobalt catalyst resulted in the corresponding 2,3-disubstituted indenones in good yields. Excellent regioselectivities were observed, when silyl aryl alkynes were used. The intermediate 3-silyl-2-aryl-substituted indenones were converted to 2,3-diaryl indenones by a three-step protocol involving C–Si bromination and Suzuki–Miyaura coupling reaction.
Regio- and stereo-selective intermolecular [2+2] cycloaddition of allenol esters with C60 leading to alkylidenecyclobutane-annulated fullerenes Mitsuhiro Ueda, Tsukasa Sakaguchi, Miho Hayama, Takafumi Nakagawa, Yutaka Matsuo, Aiko Munechika, Shunsuke Yoshida, Hiroshi Yasuda, Ilhyong Ryu Chem. Commun., 2016, 52, 89 pp. 13175 - 13178 DOI: 10.1039/C6CC07320D
The intermolecular [2+2] cycloaddition of allenol esters, which were in situ generated by Pt-catalyzed 1,3-acyloxy migration of propargylic esters, with C60 proceeded regio- and stereo-selectively to give a novel class of alkylidenecyclobutane-annulated fullerenes. The cyclobutane-annulated fullerene derivatives have high-lying LUMO levels, which gave a high open-circuit voltage in organic solar cell applications. The observed high electron mobility provided a good fill factor compared with the PCBM-based devices.
Flow Update for a Cossy Photocyclization Takahide Fukuyama, Yuki Fujita, Muhammad Abid Rashid, Ilhyong Ryu Org. Lett., 2016, 18, 20 pp. 5444 - 5446 DOI: 10.1021/acs.orglett.6b02727
A Cossy 5-exo-dig photocyclization of organohalides (X = Br, I) onto a C–C triple bond was studied using a flow photomicroreactor, which proceeded in a minute order of residence time. A deuterium labeling study supported the nonchain radical mechanism proposed by the Cossy group, in which a hydrogen source originates from a triethylamine cation radical. Scalable flow synthesis using a larger volume of flow reactor was also successful, providing 4 g of the product in high yield.
Transition-metal-free cross-coupling reaction of benzylic halides with arylboronic acids leading to diarylmethanes Mitsuhiro Ueda, Daiki Nakakoji, Yuki Kuwahara, Kota Nishimura, Ilhyong Ryu Tetrahedron Letters, 2016, 57, 37 pp. 4142 - 4144 DOI: 10.1016/j.tetlet.2016.07.089
The cross-coupling reaction between arylboronic acids and various benzylic halides proceeded without using a transition-metal catalyst to give the corresponding diarylmethanes in moderate to good yields.
Radical bromoallylation of alkynes leading to 1-bromo-1,4-dienes Takashi Kippo, kanako Hamaoka, Mitsuhiro Ueda, Takahide Fukuyama, Ilhyong Ryu Tetrahedron, 2016, 72, 48 pp. 7866 - 7875 DOI: 10.1016/j.tet.2016.05.084
The full scope (30 examples) of the radical bromoallylation of alkynes using allyl bromides was studied. In this reaction, bromine radical adds to alkynes to form vinyl radicals, which then undergo an SH2′ reaction with allyl bromides to produce good yields of 1-bromo-1,4-dienes with the liberation of a bromine radical, which creates a radical chain. The sp2-carbon–bromine bond of the product dienes was further functionalized via cross-coupling and carbonylation reactions.
Hydroalkylation of Alkenes Using Alkyl Iodides and Hantzsch Ester under Palladium/Light System Shuhei Sumino, Ilhyong Ryu Org. Lett., 2016, 18, 1 pp. 52 - 55 DOI: 10.1021/acs.orglett.5b03238
The hydroalkylation of alkenes using alkyl iodides with Hantzsch ester as a hydrogen source occurred smoothly under a Pd/light system, in a novel, tin-free Giese reaction. A chemoselective reaction at C(sp3)–I in the presence of a C(sp2)–X (X = Br or I) bond was attained, which allowed for the stepwise functionalization of two types of C–X bonds in a one-pot procedure.