98-81-7Relevant articles and documents
Anionic polymerization of 2-phenyl[3]dendralene and 2-(4-methoxyphenyl)[3] dendralene
Takenaka, Katsuhiko,Amamoto, Shuhei,Kishi, Hiroto,Takeshita, Hiroki,Miya, Masamitsu,Shiomi, Tomoo
, p. 7282 - 7289 (2013)
Anionic polymerization of two phenyl-substituted trienes containing cross-conjugated carbon-carbon double bonds, 2-phenyl[3]dendralene (P3D) and 2-(4-methoxyphenyl)[3]dendralene (MP3D), was carried out in THF under a variety of different conditions. Poly(P3D) of controlled molecular weight with a narrow molecular weight distribution was obtained when the polymerization reaction was carried out at -78 C for 30 min. Broadening of the molecular weight distribution to the higher-molecular-weight side was observed if the polymerization mixture was left to stand for 20 h at -78 C, presumably because of the attack of the propagating chain-end carbanion at the conjugated diene structure in the polymer chain. Similar broadening occurred if the polymerization was performed at a higher temperature. However, under identical conditions, no such a broadening was observed in the polymerization of MP3D. Block copolymers of predictable molecular weights and compositions containing a poly(2-vinylpyridine) segment were obtained by the sequential addition of P3D and/or MP3D to potassium naphthalenide and then 2-vinylpyridine. Only the conjugate addition structure was found in the resulting polymers.
Catalytic Asymmetric Halogenation/Semipinacol Rearrangement of 3-Hydroxyl-3-vinyl Oxindoles: A Stereodivergent Kinetic Resolution Process
Cao, Weidi,Dai, Li,Feng, Xiaoming,Hu, Xinyue,Liu, Wen,Zeng, Zi,Zhou, Yuqiao
supporting information, p. 26599 - 26603 (2021/11/16)
A highly enantioselective halogenation/semipinacol rearrangement of isatin-derived allylic alcohols has been developed with a chiral N,N′-dioxide/ScIII complex as catalyst. This strategy involved a pivotal stereodivergent kinetic resolution process and provided a facile and efficient entry to optically active halo-substituted quinolone derivatives and quinoline alkaloids with a quaternary stereocenter simultaneously under mild reaction conditions. Based on the control experiments together with kinetic studies and DFT calculations, a possible catalytic cycle was proposed to illustrate the reaction process and enantiocontrol.
Copper-Catalyzed Asymmetric Coupling of Allenyl Radicals with Terminal Alkynes to Access Tetrasubstituted Allenes
Dong, Xiao-Yang,Zhan, Tian-Ya,Jiang, Sheng-Peng,Liu, Xiao-Dong,Ye, Liu,Li, Zhong-Liang,Gu, Qiang-Shuai,Liu, Xin-Yuan
supporting information, p. 2160 - 2164 (2020/12/01)
In contrast to the wealth of asymmetric transformations for generating central chirality from alkyl radicals, the enantiocontrol over the allenyl radicals for forging axial chirality represents an uncharted domain. The challenge arises from the unique elongated linear configuration of the allenyl radicals that necessitates the stereo-differentiation of remote motifs away from the radical reaction site. We herein describe a copper-catalyzed asymmetric radical 1,4-carboalkynylation of 1,3-enynes via the coupling of allenyl radicals with terminal alkynes, providing diverse synthetically challenging tetrasubstituted chiral allenes. A chiral N,N,P-ligand is crucial for both the reaction initiation and the enantiocontrol over the highly reactive allenyl radicals. The reaction features a broad substrate scope, covering a variety of (hetero)aryl and alkyl alkynes and 1,3-enynes as well as radical precursors with excellent functional group tolerance.
