4792-33-0Relevant articles and documents
Squaramide-catalyzed asymmetric intramolecular oxa-michael reaction of α,β-unsaturated carbonyls containing benzyl alcohol: Construction of chiral 1-substituted phthalans
Son, Eun Chae,Kim, Seung Yeon,Kim, Sung-Gon
, p. 6826 - 6839 (2021/05/29)
Organocatalytic enantioselective intramolecular oxa-Michael reactions of benzyl alcohol bearing α,β-unsaturated carbonyls as Michael acceptors are presented herein. Using cinchona squaramide-based organocatalyst, enones as well as α,βunsaturated esters containing benzyl alcohol provided their corresponding 1,3-dihydroisobenzofuranyl-1-methylene ketones and 1,3-dihydroisobenzofuranyl-1-methylene esters in excellent yields with high enantioselectivities. In addition, enantioenriched 1,3-dihydroisobenzofuranyl-1-methylene ketone could be obtained from the Wittig/oxa-Michael reaction cascade of 1,3-dihydro-2-benzofuran-1-ol.
Synthesis of 3-Unsubstituted Phthalides from Aryl Amides and Paraformaldehyde via Ruthenium(II)-Catalyzed C–H Activation
Zhou, Chao,Zhao, Junqi,Chen, Wenkun,Imerhasan, Mukhtar,Wang, Jun
supporting information, p. 6485 - 6488 (2020/10/02)
A straightforward and convenient route has been developed for the synthesis of 3-unsubstituted phthalide derivatives from aryl amides and paraformaldehyde by ruthenium(II)-catalyzed C–H activation. The reaction proceeds through tandem ortho-hydroxymethylation of aryl amide and subsequent intramolecular lactonization.
Visible light mediated oxidation of benzylic sp3 C-H bonds using catalytic 1,4-hydroquinone, or its biorenewable glucoside, arbutin, as a pre-oxidant
Finney, Laura C.,Mitchell, Lorna J.,Moody, Christopher J.
supporting information, p. 2242 - 2249 (2018/05/28)
Benzylic ethers undergo a visible light induced C-H activation and oxygen insertion to give the corresponding benzoate esters in moderate to good yields. The conditions employ substoichiometric amounts of 1,4-hydroquinone with copper(ii) chloride dihydrate as an electron-transfer mediator, oxygen as the terminal oxidant and dimethyl carbonate as solvent under visible light irradiation. The naturally occurring glucoside, arbutin, which is commercially available or can be accessed via extraction of the leaves of bearberry (Arctostaphylos uva-ursi) or elephant ears (Bergenia crassifolia) can be used as a biorenewable source of 1,4-hydroquinone. The methodology exploits the increase in oxidizing ability of quinones upon irradiation with visible light, and offers a sustainable alternative for the late stage oxidative functionalization of benzylic C-H bonds. It is applicable to a range of cyclic benzylic ethers such as isochromans and phthalans, and simple benzyl alkyl ethers. It can also be applied in the oxidation of benzylic amines into amides, and of diarylmethanes into the corresponding ketones. Mechanistic studies suggest that the reaction proceeds by H-abstraction by the photo-excited triplet benzoquinone to give a benzylic radical that subsequently reacts with molecular oxygen.
