- Catalytic Highly Regioselective C-H Oxygenation Using Water as the Oxygen Source: Preparation of 17O/18O-Isotope-Labeled Compounds
-
We found that the oxygen atom of water is activated to iodosylbenzene derivatives via reversible hydrolysis of PhI(OOCR)2 and can be used to the oxygen source for ruthenium(bpga)-catalyzed site-selective C-H oxygenation. Ru(bpga)/PhI(OOCR)2/H2O system, sterically less bulky methinic and methylenic C-H bonds in various compounds can be converted to desired oxygen functional groups in a site-selective manner. Using this method, oxygen-isotope labeled compounds such as d-[3-17O/18O]-mannose can be prepared in a multigram scale.
- Doiuchi, Daiki,Uchida, Tatsuya
-
supporting information
p. 7301 - 7305
(2021/10/01)
-
- Synthesis of unstable 4-benzoyl-1,6-anhydro-3-keto-β-D-mannopyranose via stereoselective photobromination of 2,3-isopropylidene-4-benzoyl-1,6-anhydro-β-D-mannopyranose
-
Stereoselective photobromination of 1,6-anhydro-β-D-glucopyranose derivatives occurs at exo-H6. However, photobromination of 4-benzoyl-2,3-isopropylidene-1,6-anhydro-β-D-mannopyranose 6 produced unstable 4-benzoyl-1,6-anhydro-3-keto-β-D-mannopyranose 7. The mechanism of stereoselective oxidation at C-3 could be attributed to the facile radical proton abstraction at C-3, followed by the subsequent bromination of the isopropylidene group, which was subsequently eliminated during the aqueous workup. Thus, the aim of this article is to identify the molecular structure of the unstable compound 7.
- Mahdi, Jassem G.,Dawoud, Hanaa M.,Manning, Abigail J.,Lieberman, Harvey F.,Kelly, David R.
-
-
- Synthesis and reactivity of nonstabilized diazo sugars
-
1,6-Anhydro-4-deoxy-4-diazo-2,3-O-isopropylidene-β-d-lyxo-hexopyranose (4) is a stable crystalline compound readily accessible by an improved synthetic procedure. It has been used as a model for evaluating the reactivity of the diazo group, when not stabilized by an adjacent carbonyl function, in a rigid chiral matrix. A range of carbene-type, electrophile-promoted, and 1,3-dipolar reactions were evaluated, leading to 4,4′-alkene dimers, 4-deoxy-3-enose and related derivatives, 4,4-dihalo compounds, 4-spirocyclopropane derivatives, 4-spiropyrazole structures, and by skeletal rearrangement, branched-chain anhydropentose structures having a bicyclo[2.2.2] skeleton.
- Alexander, Michael S.,Horton, Derek
-
-
- A carbohydrate synthesis employing a photochemical decarbonylation
-
A new route to the aldopentoses, ribose and lyxose, and the aldohexoses, talose and gulose, has been developed using chiral building blocks containing a bicyclo[3.2.1]octane framework by employing a photochemical decarbonylation reaction as the key step.
- Kadota, Kohei,Ogasawara, Kunio
-
p. 8661 - 8664
(2007/10/03)
-
- 5-exo Radical Cyclization onto 3-Alkoxyketimino-1,6-anhydromannopyranoses. Efficient Preparation of Synthetic Intermediates for (-)-Tetrodotoxin
-
Ketoxime ethers at C3 of 1,6-anhydro-β-D-mannopyranose derivatives were found to be useful 5-exo radical traps of alkyl and vinyl radicals generated at a chain tethered to the C2 hydroxyl group, allowing advanced synthetic intermediates for (-)-tetrodotoxin to be prepared from D-mannose in good overall yield.
- Noya,Paredes,Ozores,Alonso
-
p. 5960 - 5968
(2007/10/03)
-
- 2,3,4-Tri-O-acetyl-1,6-anhydro-β-D-mannopyranose, an artifact produced during carbohydrate analysis. A total synthesis of 2,3,5-tri-O-acetyl-1,6-anhydro-β-D-mannofuranose
-
This study confirms that 2,3,4-tri-O-acetyl-1,6-anhydro-β-D-mannopyranose is an artifact produced during carbohydrate analysis. A new synthesis of 2,3,5-tri-O-acetyl-1,6-anhydro-β-D-mannofuranose is also described, and a novel dimer, 1,6':6,1'-dianhydro-2,3:2',3'-di-O-isopropylidene-5,5'-di-O-(1-methoxy ethyl)-di-α-D-mannofuranose, has been isolated. The structure of the dimer is confirmed by X-ray analysis of a derivative, 1,6':6,1'-dianhydro-2,3:2',3'-di-O-isopropylidene-di-α-D-mannofuranos e. This study confirms that 2,3,4-tri-O-acetyl-1,6-anhydro-β-D-mannopyranose is an artifact produced during carbohydrate analysis. A new synthesis of 2,3,5-tri-O-acetyl-1,6-anhydro-β-D-mannofuranose is also described, and a novel dimer, 1,6′:6,1′- dianhydro-2,3:2′,3′-di-O- isopropylidene-5,5′-di-O-(1-methoxyethyl)-di-α-D- mannofuranose, has been isolated. The structural of the dimer is confirmed by X-ray analysis of a derivative, 1,6′:6, 1′-dianhydro-2,3:2′,3′-di-O-isopropylidene- di-α-D-mannofuranose.
- Manna,McAnalley,Ammon
-
-
- NOVEL REACTIONS OF CARBOHYDRATES DISCOVERED EN ROUTE TO NATURAL PRODUCTS
-
An approach to the synthesis of tetrodotoxin is described in which two key reactions are used to establish the densely functionalized carbocyclic ring.The -bicyclic framework of 1,6-anhydro mannopyranose serves as the the template, and in the first
- Fraser-Reid, B.,Alonso, R. A.,McDevitt, R. E.,Rao, B. Venkateswara,Vite, G. D.,Zottola, M. A.
-
p. 617 - 626
(2007/10/02)
-
- Asymmetric Synthesis of 1,3-Dioxolane-Pyrimidine Nucleosides and Their Anti-HIV Activity
-
In order to study the structure-activity relationships of dioxolane nucleosides as potential anti-HIV agents, various enantiomerically pure dioxolane-pyrimidine nucleosides have been synthesized and evaluated against HIV-1 in human peripheral blood mononuclear cells.The enantiomerically pure key intermediate 8 has been synthesized in nine steps from 1,6-anhydro-D-mannose (1), which was condensed with 5-substituted pyrimidines to obtain various dioxolane-pyrimidine nucleosides.Upon evaluation of these compounds, cytosine derivative 19 was found to exhibit the most potent anti-HIV agent although it is the most toxic.The order of anti-HIV potency was as follows: cytosine (β-isomer) > thymine > cytosine (α-isomer) > 5-chlorouracil > 5-bromouracil > 5-fluorouracil derivatives.Uracil, 5-methylcytosine, and 5-iodouracil derivatives were found to be inactive.Interestingly, α-isomer 20 showed good anti-HIV activity without cytotoxicity.As expected, other α-isomers did not exhibit any significant antiviral activity. (-)-Dioxolane-T was 5-fold less effective against AZT-resistant virus than AZT-sensitive virus.
- Kim, Hea O.,Ahn, Soon K.,Alves, Antonio J.,Beach, J. Warren,Jeong, Lak S.,et al
-
p. 1987 - 1995
(2007/10/02)
-
- One-Step Stereoselective Syntheses of C-Branched α-Deoxycyclitols from 1,6-Anhydrohexopyranoses
-
1,6-Anhydro-3,4-O-isopropylidene-β-D-galactopyranose (1) reacts with n-butyllithium to give exclusively 1D-1-C-butyl-2,3-O-isopropylidene-1,2,3,5/4-cyclohexanepentol (2a). 1,6-Anhydro-2,3-O-isopropylidene-β-D-mannopyranose (7) gives 1L-5-C-butyl-2,3-O-isopropylidene-1,2,3/4,5-cyclohexanepentol (8a) and 1L-1-C-butyl-3,4-O-isopropylidene-1,2,5/3,4-cyclohexanepentol (9a) as a by-product.Analogous reactions with methyllithium yield the corresponding C-methyl-branched deoxyinositols 2b, 4, 8b, and 9b.
- Klemer, Almuth,Kohla, Monika
-
p. 1662 - 1671
(2007/10/02)
-
