A highly diastereoselective synthesis of 4-octulose and 2-deoxy-4-octulose from a -fructose derivative

Bishydroxylation of methyl

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1 with osmium tetraoxide proceeded with extremed high diastereoselectivity to give only methyl

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2. Configurations of the new stereogenic centers (C-2,3) in 2 were determined by degradation of the C-5,6,7,8 fragment to the well-known methyl

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7. Transformation of 2 into the required

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10, was achieved by a methodology that implied, protection to 8, reduction of the ester group in 8 to a hydroxymethyl group in 9, and finally deprotection to the free

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10. On the other hand, epoxidation reaction on

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11 afforded only the corresponding 2,3-anhydro derivative 12 with configuration, as could be demonstrated by degradation to (S)-1,2,4-trimetoxybutane 16, which synthesis is reported herein.     

Efficient stereoselective synthesis of a 1-hydroxymethyl-2-methylglycidol derivative

A highly stereoselective synthesis of (2R,3S)-3,4-epoxy-3-methyl-1-(triphenylmethyl)oxybutan-2-ol 3, which is a substructure found in some naturally-occurring bioactive compounds, was achieved starting from commercially available 3-methyl-2-buten-1-ol 4 in three steps, using two applications of the Sharpless asymmetric epoxidation as the key stereochemistry establishing reactions.     

Straightforward synthesis of a derivative of purpurosamine C from d-galactose

Purpurosamine C (1) is a component of the aminoglycoside antibiotic gentamicin C_1a. A derivative of 1 was synthesized from d-galactose via its 2-acetoxy-3,4,6-tri-O-acetyl glycal (3). Compound 3 undergoes glycosylation with 2-propanol in the presence of SnCl₄, with two succesive allylic rearrangements of the double bond to give isopropyl 6-O-acetyl-3,4-dideoxy-α-d-glycero-hex-3-enopyranosid-2-ulose (7). Compound 7 was hydrogenated, and O-deacetylated to afford 8. The free OH group of 8 was tosylated and substituted by azide, and the carbonyl function of the resulting ulose 10 reacted with hydroxylamine to give the E,Z-oximes (11,12). Highly diastereoselective reduction of the oxime acetate (13) by borane, which also reduced the azide function, led to the purpurosamine C derivative 14 (∼40% yield from 3).     

Design and synthesis of a solid-supported FR225659 derivative for its receptor screening

[structure: see text] We describe the design and synthesis of latex particles attached to an FR225659 derivative to identify its receptor proteins. Two key building blocks were prepared by two-step degradation of FR225659 under basic conditions. The designed ligand showed an acceptable level of biological activity to make it of potential value for use in affinity-supported receptor identification. Affinity purification of FR225659-binding proteins using the latex nanoparticles provided three candidate receptor peptides for the biological activity.     

A simple five-step synthesis of a pentadecaalkylcorrin derivative from commercial cyanocobalamin

Dicyano 2,7,18-triethyl-1,2,5,7,12,12,15,17-octamethyl-3,8,13,17-tetrapropyl-Co(III)-corrin has been prepared by reduction of the ester groups of dicyano cobyrinic acid heptamethylester.     

New synthesis of pyridone derivative from 1-azadiene

The reaction of 1-azabutadienes with enolates of substituted acetates gave 3,4-dihydro-2-pyridones which rearrange or dehydrogenate to other isomeric dihydropyridones or pyridones. Thus 1-azabutadienes were found to be good building blocks for pyridone derivatives.     

Novel synthesis of a strained para-cyclophane derivative

A [P. Rajakumar, A.M.A. Rasheed, Tetrahedron 61（22） （2005） 5351] para-cyclophane derivative was synthesized via intramolecular esterification of a dipeptide surrogate containing asparagine to form tetrahydropyrimidinone ring. The structures of the product and intermediates were characterized by 1H NMR, 13C NMR and mass spectrum.     

The synthesis of a menthol derivative of 2-aminopurine as a fluorescent DNA lesion

An efficient synthetic route to the phosphoramidite of a menthol functionalized guanosine analog is presented. Two procedures were executed for the key introduction of the 6′-allyl menthyl moiety. Stille vinylation on 6-O-tosylguanosine followed by cross-metathesis using an excess of allyl menthyl ether proved to be less efficient than a Stille coupling on the same tosylate using an advanced menthyl-allyl stannane derivative. Incorporation of the modified nucleoside using the phosphoramidite method into a DNA 50-mer proceeded uneventfully.     

First total synthesis of justicidone, a p-quinone-lignan derivative from Justicia hyssopifolia

The first synthesis of justicidone (4-(1',3'-Benzodioxol-5'-yl)-6-methoxynaphtho[2,3-c]furan-1,5,8(3H)-trione) was carried out from piperonal, as a starting compound, through a lineal process using well known reactions.     

An unusual synthesis of a spirothioxanthene derivative

The reaction of diphenyl sulfone with 2,3-dibromophthalazine-1,4-dione in the presence of n-butyllithium gave a spiro-9H-thioxanthene-10,10-dioxide derivative in 45% yield, the structure of which was proved by X-ray crystallography.     

Isolation and synthesis of aplysinadiene,a new rearranged dibromotyrosine derivative from aplysina aerophoba

From the sponge Aplysina aerophoba a new rearranged dibromotyrosinederivative aplysinadiene (9) was isolated. The structure was solved by spectral properties and synthesis.     

One-step synthesis of a fluorescein derivative and mechanistic studies

We report a convenient method for the one-step synthesis of a fluorescein derivative under acidic conditions. Mechanistic studies indicate that the acid-promoted condensation of o-tolualdehyde and 4-chlororesorcinol to form the fluorescein derivative proceeds through a cyclization-oxidation pathway while an alternative oxidation-cyclization pathway remains possible.     

The synthesis of a monoammonium derivative of fullerenopyrrolidine

The Prato reaction was used to synthesize a monoammonium derivative of fullerenopyrrolidine. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1491–1492, June, 2005.     

Attempted synthesis of a substituted [2.2.2]propellane derivative from triptycene derivatives

Bromotriptycene derivatives substituted at the bridgehead were subjected to varying reaction conditions in the attempt to obtain a substituted [2.2.2]propellane. The desired cyclization was not effected. The bromine atoms were replaced by hydrogens.     

Enzymatic synthesis of a soluble polyphenol derivative from 4,4′-biphenyldiol

Enzymatic oxidative polymerization of 4,4′-biphenyldiol was performed in an aqueous organic solvent using horseradish peroxidase as catalyst. In the polymerization using a mixture of 1,4-dioxane and phosphate buffer (pH 7.0) (80:20 vol-%) as solvent, the monomer was quantitatively consumed to give powdery polymeric materials in a high yield. The resulting polymer is soluble in polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and acetone. The molecular weight of the methylated product is 7.3 × 10³. The polymer exhibits high thermal stability under nitrogen.     

Improved synthesis of a functionalized 2,8-ethanonoradamantane derivative

An improved preparation of a functionalized 2,8-ethanonoradamantane derivative, which avoids two protection/deprotection steps while deprotection of a benzyloxymethyl protecting group takes place during an acid-catalyzed dehydration, is described. Altogether the synthesis has been reduced in five steps (from 16 to 11 steps) with an increase in the global yield from 5.8 to 7.2%.     

Stereoselective synthesis of a new methyl-substituted inositol derivative

The stereoselective synthesis of methyl-substituted inositol derivative is described. Diene diacetate which is a key compound was first prepared via three steps starting from 2-methyl-p-benzoquinone. Osmium-catalyzed regio- and stereoselective dihydroxylation of diene diacetate afforded cis-diol diasetate, which then produced tetra acetate via acetylation with Ac₂O-pyridine. Oxidation and acetylation of the other alkene moiety in the compound gave a hexaacetate compound stereoselectively. Finally, the acetate groups were removed by NH₃ leading to formation of the desired new methyl-substituted inositol derivative having a muco-inositol-type stereochemical pattern in the six-membered ring. Spectroscopic methods were used for characterization of all synthesized compounds.     

Efficient synthesis of a configurationally stable l-serinal derivative

An efficient synthesis of a configurationally stable l-serinal derivative 8 was achieved using an N-hydroxymethyl group in about 50% overall yield in four steps from l-serine. Not more than 1% racemization was observed during the preparation of 8. Its enantiomeric integrity was maintained for at least 15 days at room temperature, and it was stable on silica gel. The orthogonal protective groups of 8 would make it a useful chiral synthon.