122086-39-9Relevant articles and documents
Symmetry-Driven Strategy for the Assembly of the Core Tetracycle of (+)-Ryanodine: Synthetic Utility of a Cobalt-Catalyzed Olefin Oxidation and α-Alkoxy Bridgehead Radical Reaction
Nagatomo, Masanori,Hagiwara, Koji,Masuda, Kengo,Koshimizu, Masaki,Kawamata, Takahiro,Matsui, Yuki,Urabe, Daisuke,Inoue, Masayuki
, p. 222 - 229 (2016)
Ryanodine (1) is a potent modulator of intracellular calcium release channels, designated as ryanodine receptors. The exceptionally complex molecular architecture of 1 comprises a highly oxygenated pentacyclic system with eleven contiguous stereogenic centers, which makes it a formidable target for organic synthesis. We identified the embedded C2-symmetric tricyclic substructure within 1. This specific recognition permitted us to design a concise synthetic route to enantiopure tricycle 9 by utilizing a series of pairwise functionalizations. The four tetrasubstituted carbon centers of 9 were effectively constructed by three key reactions, a dearomatizing Diels-Alder reaction, the kinetic resolution of the obtained racemic 14 through asymmetric methanolysis, and the transannular aldol reaction of the eight-membered diketone 10. A new combination of cobalt-catalyzed hydroperoxidation and NfF-promoted elimination enabled conversion of the hindered olefin of 9 into the corresponding ketone, thus realizing the desymmetrization. Finally, the tetrasubstituted carbon was stereospecifically installed by utilizing the α-alkoxy bridgehead radical to deliver the core tetracycle 7 with the six contiguous tetrasubstituted carbon centers. Consequently, the present work not only accomplishes efficient assembly of four out of the five fused rings of 1, but also develops two new powerful methodologies: two-step ketone formation and bridgehead radical reaction.
A KI-mediated radical anti-Markovnikov addition of simple ketones/esters to unactivated alkenes
Tian, Yunfei,Sun, Changqing,Tan, Ren Xiang,Liu, Zhong-Quan
supporting information, p. 588 - 592 (2018/02/14)
A KI-mediated radical anti-Markovnikov addition of simple ketones and esters to unactivated alkenes was developed. Through this strategy, a wide range of complex carbonyl compounds can be conveniently synthesized in high selectivities. In addition, this method features high atom-economy and is transition-metal free, operationally simple and environmentally benign.
Cobaloxime-catalyzed hydration of terminal alkynes without acidic promoters
Hou, Shengtai,Yang, Hongjian,Cheng, Bin,Zhai, Hongbin,Li, Yun
supporting information, p. 6926 - 6929 (2017/07/10)
Cobaloxime (Co(dmgBF2)2·2H2O), an inexpensive first-row transition-metal complex, catalyzed hydration of terminal alkynes gave the corresponding methyl ketones in good to excellent yields under neutral conditions (additional protic acids and silver salts are not required). A wide range of functional groups, such as allyl ether, benzyl ethers, carboxylic esters, imides, amides, nitro, and halogens, were tolerated. The mild reaction conditions together with the inexpensive feature and easy availability of the catalyst well address the current challenges in the field of alkyne hydration.
