105401-83-0Relevant academic research and scientific papers
A Catalytic Deprotection of S,S-, S,O- and O,O-Acetals Using Bi(NO3)3·5 H2O under Air
Komatsu, Naoki,Taniguchi, Azusa,Wada, Shinobu,Suzuki, Hitomi
, p. 473 - 480 (2001)
S,S-Acetals are smoothly deprotected with air in the presence of a catalytic amount of Bi(NO3)3·5 H2O (1-50 mol %) under ambient conditions to regenerate the original carbonyl compounds in good to excellent yield. This mild, simple, and environmentally benign system is successfully applied to the deprotection of S,O- and O,O-acetals and is compatible with various functional groups. From the mechanistic study of the reaction, the catalytic cycle is considered to be composed of the following four steps: (1) the nitrososulfonium ion of the S,S-acetal is formed by attack of nitrosonium ion (NO+) generated from Bi(NO3)3·5 H2O through the equilibrium wth NO2, (2) the nitrososulfonium ion is hydrolyzed to afford the hemithioacetal and thionitrite, (3) the hemithioacetal collapses to the original carbonyl compound and thiol, which is oxidized by NO+ to give disulfide and NO via thionitrite, and (4) the NO captures molecular oxygen from air to regenerate NO2.
Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey–Seebach Reaction
Crespi, Stefano,Donabauer, Karsten,K?nig, Burkhard,Murugesan, Kathiravan,Rozman, Ur?a
supporting information, p. 12945 - 12950 (2020/09/23)
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C?H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
Unusual formation of cyclic-orthoesters by Pd(II)-mediated cyclization-carbonylation of propargylic acetates
Kato, Keisuke,Yamamoto, Yasuhiro,Akita, Hiroyuki
, p. 6587 - 6590 (2007/10/03)
The oxidative cyclization-methoxycarbonylation of propargylic acetates 1 in the presence of (CH3CN)2PdCl2/p-benzoquinone in methanol under carbon monoxide atmosphere (balloon) afforded (E)-cyclic-orthoesters 5 in moderate
