25017-79-2Relevant academic research and scientific papers
Visible-light-driven palladium-catalyzed Dowd-Beckwith ring expansion/C-C bond formation cascade
Chen, Li,Guo, Li-Na,Liu, Shuai,Liu, Le,Duan, Xin-Hua
, p. 1791 - 1795 (2021/02/22)
A visible-light-induced palladium-catalyzed Dowd-Beckwith ring expansion/C-C bond formation cascade is described. A range of six to nine-membered β-alkenylated cyclic ketones possessing a quaternary carbon center were accessed under mild conditions. Besides styrenes, the electron-rich alkenes such as silyl enol ethers and enamides were also compatible, providing the desired β-alkylated cyclic ketones in moderate to good yields.
Biocatalytic access to nonracemic γ-oxo esters: Via stereoselective reduction using ene-reductases
Turrini, Nikolaus G.,Cioc, Rǎzvan C.,Van Der Niet, Daan J. H.,Ruijter, Eelco,Orru, Romano V. A.,Hall, Mélanie,Faber, Kurt
supporting information, p. 511 - 518 (2017/08/14)
The asymmetric bioreduction of α,β-unsaturated γ-keto esters using ene-reductases from the Old Yellow Enzyme family proceeds with excellent stereoselectivity and high conversion levels, covering a broad range of acyclic and cyclic derivatives. Various strategies were employed to provide access to both enantiomers, which are versatile precursors of bioactive molecules. The regioselectivity of hydride addition on di-activated alkenes was elucidated by isotopic labeling experiments and showed strong preference for the keto moiety as activating/binding group as opposed to the ester. Finally, chemoenzymatic synthesis of (R)-2-(2-oxocyclohexyl)acetic acid was achieved in high ee on a preparative scale combining enzymatic reduction followed by ester hydrogenolysis.
Biocatalytic synthesis of chiral cyclic γ-oxoesters by sequential C-H hydroxylation, alcohol oxidation and alkene reduction
Brenna, Elisabetta,Crotti, Michele,Gatti, Francesco G.,Monti, Daniela,Parmeggiani, Fabio,Pugliese, Andrea,Tentori, Francesca
supporting information, p. 5122 - 5130 (2017/11/09)
A three-step biocatalytic procedure is described for the conversion of methyl and ethyl cyclopentene- and cyclohexenecarboxylates into both the enantiomers of the corresponding chiral 3-oxoesters, which are useful building blocks for the synthesis of active pharmaceutical ingredients. The allylic hydroxylation of the starting cycloalkenecarboxylates is carried out by using R. oryzae resting cells entrapped in alginate beads, in acetate buffer solution at 25 °C. The oxidation of the intermediate allylic alcohols to unsaturated ketones, performed by the laccase/TEMPO system, and the ene-reductase mediated hydrogenation of the alkene bond were carried out in the same reaction vessel in a sequential mode at 30 °C. Being entirely biocatalytic, our multistep procedure provides considerable advantages in terms of selectivity and environmental impact over reported chemical methods.
Free-Radical Ring Expansion by one Carbon Atom by Decomposition of the Thiohydroxamic Esters of (1-Alkoxycarbonyl-2-oxocycloalkyl)acetic Acids
Matovic, Radomir,Cekovic, Zivorad
, p. 483 - 488 (2007/10/03)
A free-radical ring expansion by one carbon atom has been achieved by thermal decomposition of thiohydroxamic esters of (1-alkoxycarbonyl-2-oxocycloalkyl)acetic acids, 8.Thus, by decomposition of thiohydroxamic esters 8a-f in boiling toluene, ethyl 3-oxocycloalkenecarboxylates 9a-f are obtained as principal ring-enlarged products in 27-58percent yield; accompanied by ethyl 1-(4-methyl-2-thiazolylthio)-3-oxocycloalkane-1-carboxylates 10c,d (24percent yield) with the ring expanded by one carbon atom.Unrearranged ethyl 1-(4-methyl-2-thiazolylthiomethyl)-2-oxocycloalkane-1-carboxylates) 11a-f are formed as side products (8-17percent yield).Ring expansion involves the following sequence of reactions: 3-exo-cyclization (to C=O grup), cleavage of the cyclopropane ring, intermolecular addition to the thione group of thiohydroxamic esters and elimination reaction.
Control of the Birch Reduction of m-Anisic Acid to Produce Specific 3-Oxocyclohexenecarboxylic Acids
Webster, Francis X.,Silverstein, Robert M.
, p. 922 - 924 (2007/10/02)
An efficient method is reported of synthesizing relatively large quantities of methyl 3-oxo-1-cyclohexenecarboxylate (2b), a useful dienophile and photoreagent, from m-anisic acid (3) through the Birch reduction.Treating 3 with lithium in liquid ammonia p
A MIMIC STUDY ON COENZYME-B12 USING ORGANOCOBALOXIMES. THE REARRANGEMENT OF 1-SUBSTITUTED-2-OXOCYCLOPENTYLMETHYL RADICAL
Tada, Masaru,Miura, Kyo,Okabe, Masami,Seki, Shigetaka,Mizukami, Hideyuki
, p. 33 - 36 (2007/10/02)
The radical cleavage of the carbon-cobalt bond of 1-phenyl-2-oxocyclopentylmethyl cobaloxime (1) and 1-ethoxycarbonyl-2-oxocyclopentylmethyl cobaloxime (2) gave only 3-phenylcyclohex-2-enone (7) and 3-ethoxycarbonylcyclohex-2-enone (8), respectively, by acyl migration.This rearrangement may be a reasonable mimicry of the ester migration mediated by coenzyme-B12.
