121671-77-0Relevant articles and documents
Primary Anion–π Catalysis of Epoxide-Opening Ether Cyclization into Rings of Different Sizes: Access to New Reactivity
Matile, Stefan,Paraja, Miguel
supporting information, p. 6273 - 6277 (2020/02/28)
The concept of anion–π catalysis focuses on the stabilization of anionic transition states on aromatic π surfaces. Recently, we demonstrated the occurrence of epoxide-opening ether cyclizations on aromatic π surfaces. Although the reaction proceeded through unconventional mechanisms, the obtained products are the same as those from conventional Br?nsted acid catalysis, and in agreement with the Baldwin selectivity rules. Different mechanisms, however, should ultimately lead to new products, a promise anion–π catalysis has been reluctant to live up to. Herein, we report non-trivial reactions that work with anion–π catalysis, but not with Br?nsted acids, under comparable conditions. Namely, we show that the anion–π templated autocatalysis and epoxide opening with alcoholate–π interactions can provide access to unconventional ring chemistry. For smaller rings, anion–π catalysis affords anti-Baldwin oxolanes, 2-oxabicyclo[3.3.0]octanes, and the expansion of Baldwin oxetanes by methyl migration. For larger rings, anion–π templated autocatalysis is thought to alleviate the entropic penalty of folding to enable disfavored anti-Baldwin cyclizations into oxepanes and oxocanes.
Structure–activity relationship studies of atpenin A5 analogs with chemical modification of the side chain moiety
Ohtawa, Masaki,Yano, Keisuke,Miyao, Atsuyoshi,Hiura, Tohru,Sugiyama, Kouhei,Arima, Shiho,Kita, Kiyoshi,Omura, Satoshi,Nagamitsu, Tohru
supporting information, p. 1037 - 1042 (2019/03/21)
We designed and synthesized new atpenin A5 analogs for SAR study. Most of the analogs lacked one or several functional groups in the side chain of atpenin A5, and the stereoisomers proved to be weak nematode complex II inhibitors. However, we determined t
Expanding the scope of methyl xanthate esters - From Barton-McCombie reaction auxiliary to versatile protective group
Thorsheim, Karin,Manner, Sophie,Ellervik, Ulf
, p. 6329 - 6333 (2017/09/29)
The methyl xanthate ester is presented as a versatile protective group for alcohols. Hydroxyl groups can easily be transformed into methyl xanthate esters by several methods and are commonly used as an auxiliary in the Barton-McCombie reaction. We show that these methyl xanthate esters can readily and chemoselectively be cleaved under mild conditions by the action of diethylenetriamine using microwave heating. This method is orthogonal to many common hydroxyl protective groups that can be introduced and cleaved in the presence of methyl xanthate ester.
