20883-99-2Relevant academic research and scientific papers
Mizoroki-Heck Reaction of Unstrained Aryl Ketones via Ligand-Promoted C-C Bond Olefination
Wang, Mei-Ling,Xu, Hui,Li, Han-Yuan,Ma, Biao,Wang, Zhen-Yu,Wang, Xing,Dai, Hui-Xiong
, p. 2147 - 2152 (2021/04/05)
Mizoroki-Heck reaction of unstrained aryl ketone with acrylate/styrene is accomplished via palladium-catalyzed ligand-promoted C-C bond cleavage. Various (hetero)aryl ketones are compatible in the reaction, affording the alkene product in good to excellent yields. Further applications in the late-stage olefination of some drugs, natural products, and fragrance-derived aryl ketones demonstrate the synthetic utility of this protocol. By employing ketone as both the directing group and the leaving group, 1,2-bifunctionalization is achieved via sequential ortho-C-H alkylation/ipso-Heck olefination.
Pd-catalyzed sequential C-C bond formation and cleavage: Evidence for an unexpected generation of arylpalladium(II) species
Youn, So Won,Kim, Byung Seok,Jagdale, Arun R.
supporting information; experimental part, p. 11308 - 11311 (2012/08/28)
A Pd(II)-catalyzed reaction engaging alkenyl β-keto esters is reported that leads to the formation of 1-naphthols and an unexpected generation of arylpalladium(II) species. Interception of the in situ generated arylpalladium(II) species in a Mizoroki-Heck reaction, together with additional mechanistic studies, provided strong evidence in support of the first aromatization-driven β-carbon elimination process. A single Pd catalyst served to promote a series of both C-C bond forming and cleavage events in an unprecedented manner.
Synthesis of chondramide a analogues with modified β-tyrosine and their biological evaluation
Zhdanko, Alexander,Schmauder, Anke,Ma, Christopher I.,Sibley, L. David,Sept, David,Sasse, Florenz,Maier, Martin E.
supporting information; experimental part, p. 13349 - 13357 (2012/02/14)
Starting from cinnamates 9, obtained by Wittig reaction or Heck coupling, the diols 17 were prepared by asymmetric dihydroxylation. This was followed by a regioselective substitution of the 3-OH group with hydrazoic acid under Mitsunobu conditions. Methylation of the 2-OH group and reduction of the azide group led to the β-tyrosine derivatives 8. Condensation with the dipeptide acid 6 furnished the tripeptide part of the chondramides. The derived acids 21 were combined with the hydroxy ester 7 to the esters 22. Cleavage of the tert-butyl groups and intramolecular lactam formation gave rise to the chondramide A analogues 2 b-k. Growth inhibition assays showed most of the analogues to be biologically active. Some of them even reach the activity of jasplakinolide. It can be concluded that the 4-position of the aryl ring in the β-tyrosine of chondramide A tolerates structural modifications quite well.
Controlled photocycloaddition of unsaturated carboxylates intercalated in hydrotalcite clay interlayers
Takagi, Katsuhiko,Shichi, Tetsuya,Usami, Hisanao,Sawaki, Yasuhiko
, p. 4339 - 4344 (2007/10/02)
Photochemical cycloaddition for several unsaturated carboxylates has been studied in the presence of hydrotalcite clays. Syn head-to-head cyclodimers were selectively formed in the irradiation of sodium cinnamates intercalated in the dispersed clays. On the other hand, two isomers of syn head-to-head and syn head-to-tail cyclodimers were formed for the case of (phenylethenyl)benzoates. The degree of intercalation was shown to be dependent on the structures of the carboxylates. X-ray diffraction analyses revealed that the carboxylates are intercalated as a monolayer, which suggests an alternate anti-parallel packing since a clay interlayer possesses two ionic surfaces, top and bottom. The product selectivity was shown to be controlled by the relative distances of double bonds from the ionic surfaces of the clay. The molecular aggregates of intercalated carboxylates were affected by adding photoinactive coadsorbates; the major photochemical processes shifted from photocycloadditions to cis-trans isomerizations and from excimer to monomer fluorescence emissions.
