- Synthesis of Furo[2,3-b]pyran-2-ones through Ag(I)- or Ag(I)-Au(I)-Catalyzed Cascade Annulation of Alkynols and α-Ketoesters
-
Ag(I)- or Ag(I)-Au(I)-catalyzed cascade annulation of alkynols (5-hexyn-1-ol systems) with α-ketoesters involving a dual activation process (π and σ) has been developed for the first time. This reaction proceeds through cycloisomerization of alkynol to give the 6-endo-enol ether followed by annulation with an α-ketoester to furnish furo[2,3-b]pyran-2-ones in good yields. Chemical structures of all products were rigorously confirmed by single crystal X-ray analysis and analogy.
- Thorat, Sagar S.,Kataria, Priyanka,Kontham, Ravindar
-
p. 872 - 875
(2018/02/09)
-
- FURO[2,3-B]PYRAN-2-ONE COMPOUNDS AND PROCESS FOR PREPARATION THEREOF
-
The present invention discloses a novel furo[2,3-b]pyran-2-one compound of formula (I) and a single step process for the preparation of furo[2,3-b]pyran-2-ones using Lewis acid-promoted cascade annulation of alkynols and α-ketoesters.
- -
-
Page/Page column 28-29
(2019/01/04)
-
- Cyclic Ether Synthesis via Palladium-Catalyzed Directed Dehydrogenative Annulation at Unactivated Terminal Positions
-
Here, a palladium-catalyzed functionalization of unactivated sp3 C-H bonds with internal alcohol nucleophiles is described. Directed by an oxime-masked alcohol, annulation chemoselectively occurs at the β position, leading to a range of aliphatic cyclic ethers with four- to seven-membered rings. Tethered primary, secondary, and tertiary free hydroxyl groups can all react to give the corresponding cyclized products. In addition, benzyl and silyl protected alcohols can also be directly coupled. An sp3 C-H activation/intramolecular SN2 pathway was proposed.
- Thompson, Samuel J.,Thach, Danny Q.,Dong, Guangbin
-
supporting information
p. 11586 - 11589
(2015/09/28)
-
- Cyclohexylamine oxidase as a useful biocatalyst for the kinetic resolution and dereacemization of amines
-
The biocatalytic performance of a cloned cyclohexylamine oxidase derived from Brevibacterium oxydans IH-35A towards structurally different amines was investigated. Cycloalkyl primary amines, alkyl aryl amines, and α-carbon-substituted aliphatic amines were identified as suitable substrates for the biocatalyst based on an activity assay. Kinetic resolutions of several amines by either recombinant whole cells or crude enzyme extracts prepared therefrom gave enantiomerically pure (R)-amines besides the corresponding ketones. When cyclohexylamine oxidase in combination with a borane-ammonia complex as reducing agent was applied to the deracemization of several substrates, excellent enantiomeric ratios (>99:1) and good isolated yields (62%-75%) of the corresponding (R)-amines were obtained.
- Leisch, Hannes,Grosse, Stephan,Iwaki, Hiroaki,Hasegawa, Yoshie,Lau, Peter C.K.
-
experimental part
p. 39 - 45
(2012/03/07)
-
- Organic electrosynthesis using toluates as simple and versatile radical precursors
-
The electrolysis of toluate esters leads smoothly to the formation of the radical of the alkyl fragment. This property has been used to develop a new electrochemical deoxygenation reaction. The Royal Society of Chemistry.
- Lam, Kevin,Marko, Istvan E.
-
supporting information; experimental part
p. 95 - 97
(2009/03/11)
-
- Functionalization of non-activated C-H bonds in ketones and imines with HF/SbF5/CCl4
-
Reaction of cyclic ketones 2-6 and imines 15-17 in HF/SbF5 in presence of CCl4 yield hydroxy or fluoroderivatives, hydride abstraction occurring at a site located far from the functional group. Whereas ketones 2-5 yield only hydroxy derivatives, through cyclic carboxonium ion, imines 15, 16 N-protonated in the media conditions give only fluoroderivatives 18, 19, respectively, after quenching with HF-pyridine. Ring contraction is operative when starting from large membered ring ketones 24 and 25, and imine 26, leading to a mixture of hydroxy or fluoro cyclohexanones and/or cycloheptanones.
- Thibaudeau, Sébastien,Martin-Mingot, Agnès,Jouannetaud, Marie-Paule,Jacquesy
-
p. 6643 - 6649
(2007/10/03)
-
- Fluorination or hydroxylation of non activated C-H bonds in amides and ketones using CCl4 or NBS in superacids
-
Amides and ketones are fluorinated or hydroxylated in HF-SbF5 in the presence of CCl4 or NBS, reaction occurring at a carbon far located from the functional group.
- Martin, Agnes,Jouannetaud, Marie-Paule,Jacquesy, Jean-Claude
-
p. 2967 - 2970
(2007/10/03)
-
- STUDIES IN ACETALIZATION REACTIONS OF SOME TERPENES
-
The reactions of some terpenic ketones / aldehydes with alcohols were investigated in acidic medium.Some expected and unexpected products have been identified and possible mechanistic pathways leading to the products are discussed.
- Anac, Olcay,Talinli, Naciye
-
-
- CYCLIZATION OF ACYCLIC ISOPRENOIDS. IV. RING CLOSURE WITH FORMATION OF A C2-OXYGEN BOND
-
Experimentally substantiated schemes are proposed for the first time for the cyclization of a series of the most important representatives of acyclic isoprenoids (citral, diisopentenylacetone, dehydrolinalool), and the intermediate carbocations were detected by NMR.In all cases the proton adds at the 2,3-double bond, and cyclization takes place by reaction of the C2 cationic center with the oxygen of the carbonyl or hydroxyl group.The cyclization of the structural analog of citral (citronellal) takes place in a different way.In this case the 2,3-double bond acts as internal nucleophile.The great synthetic possibilities of the cyclization of acyclic isoprenoids in superacids in comparison with the conditions of acid catalysis are demonstrated.
- Gavrilyuk, O. A.,Korchagina, D. V.,Osadchii, S. A.,Barkhash, V. A.
-
p. 871 - 885
(2007/10/02)
-