Total synthesis of cyclic tetrapeptide FR235222, a potent immunosuppressant that inhibits mammalian histone deacetylases

[structure: see text] The total synthesis of FR235222, a potent immunosuppressant with in vivo activities, has been achieved. The key steps include assembling its (2S,9R)-2-amino-9-hydroxy-8-oxodecanoic acid residue via an olefin cross-metathesis of a methyl (R)-lactate-derived homoallyl ketone with protected allyl amino acid and constructing its trans-(2R,4S)-4-methylproline unit from protected (R)-pyroglutamic acid in seven steps.     

Synthese von selektiv N- funktionalisierten Polyamin-Derivaten

Synthesis of Selectively N-Functionalized Polyamine Derivatives A threefold differently protected derivative 8 of the triamine spermidine ( 2 ) has been prepared in three steps starting from propane-1,3-diamine ( 1 ). The protected spermidine derivative 8 was converted to its spermine analogue 12 , a useful polyamine intermediate. In a convergent way, the fourfold differently protected derivative 18 of the tetraamine spermine ( 3 ) has been obtained by coupling the two different and separately prepared propane-1,3-diamine units 15 and 17 . Spermidine derivative 19 and spermine derivative 20 , both selectively protected at both primary amino groups, have been Prepared from the free polyamines 2 and 3 , respectively, in a direct approach.     

Synthesis of protected （2S,4R）-2-amino-4-methyldecanoic acid,a proposed component of culicinins

The protected （2S,4R）-2-amino-4-methyldecanoic acid, a proposed component of culicinins has been synthesized over 10 steps and in total 28% yields using Wittig reaction and Schollkopf amino acid synthesis as key steps.     

Three-step synthesis of cyclopropyl peptidomimetics

An efficient approach to novel cyclopropyl peptidomimetics has been developed. The synthetic route involves a cyclopropanation using ethyl (dimethylsulfuranylidene)acetate (EDSA) as the key step and affords a cyclopropyl peptidomimetic core in three steps from protected amino acid Weinreb amides.     

Total synthesis of (+)-blasticidin s

The first total synthesis of the peptidyl nucleoside antibiotic, blasticidin S (1), has been achieved by the coupling reaction of cytosinine (3) and blastidic acid (2). A key step in the synthesis of cytosinine (3) is the sigmatropic rearrangement of allyl cyanate 24; this reaction provided efficient and stereoselective access to 2,3-dideoxy-4-amino-D-hex-2-enopyranose (26 a). Further elaboration of 26 a gave methyl hex-2-enopyranouronate 29, and cytosine N-glycosylation of 31 using the Vorbrüggen conditions for the silyl Hilbert-Johnson reaction furnished the differentially protected cytosinine (32) in 11 steps from 2-acetoxy-D-glucal (14) (4.0 % overall yield). Synthesis of the Boc-protected blastidic acid 47 in nine steps starting from chiral carboxylic acid 35 (23 % overall yield) utilized Weinreb's protocol for the preparation of benzyl amide 38 and Fukuyama's protocol for the synthesis of the secondary amine 40. Assembly of the protected cytosinine (32) and blastidic acid (47) by the BOP method in the presence of HOBt, and finally elaboration to 1 by deprotection of the fully protected 54 established the total synthesis of blasticidin S (1).     

Synthesis of lupinacidins A and B via sequential cycloaddition-double elimination

The first synthesis of lupinacidins A and B, tumor cell invasion inhibitors of microbial origin, has been achieved in four operational steps from 3-methoxy-2-methyl-2-cyclohexenone via the Diels-Alder cycloaddition of a conjugated cyclohexadiene derivative with a juglone-derived sulfinyl quinone followed by sequential elimination of a sulfenic acid and ethylene to afford protected forms of the target molecules.     

(±)-Yaequinolone A2的简洁全合成

由廉价的邻氨基苯甲酸为起始原料经6步反应以27.8%的总产率首次合成了2-喹啉酮类生物碱(±)-yaequinolone A2,关键步骤为MOM保护的α-羟基酰胺进行的高非对映选择性分子内aldol 反应。     

Total syntheses of (+/-)-anchinopeptolide D and (+/-)-cycloanchinopeptolide D

The first synthesis of (+/-)-anchinopeptolide D (4) has been accomplished in seven steps in 10% overall yield from octopamine hydrochloride (17), N-(Boc)glycine (16), and 5-amino-2-hydroxypentanoic acid (22). The key step is the aldol dimerization and hemiaminal formation of alpha-keto amide 26, which gives primarily protected anchinopeptolide D 27 under kinetically controlled conditions. Cycloanchinopeptolide D (31) has been prepared by the unprecedented head-to-head photodimerization of the two hydroxystyrylamides of 4 using the hydrophobic effect in water to force the two side chains into close proximity so that [2 + 2] cycloaddition is faster than trans to cis double bond isomerization. Coupling of amine 21 with pyroglutamic acid affords the naturally occurring tripeptide 35, which had been assigned glutamic acid structure 34.     

Volumetric studies in oxidation-reduction reactions: Reduction with ferrous ethylenediamine sulphate ceric sulphate method

Ferrous ethylenediamine sulphate has been used as a reducing agent in acid medium for the indirect volumetric estimations of potassium chlorate, potassium bromate, potassium metaperiodate, potassium dichromate, potassium ferricyanide, potassium permanganate, potassium persulphate, hydrogen peroxide and ceric sulphate. The excess of ferrous ethylenediamine sulphate added to each of the substances in acid medium was titrated with standard ceric sulphate solution using ferroin as an indicator.     

One-pot conversion of glycals to cis-1,2-isopropylidene-alpha-glycosides

Described is a general method for the conversion of glycals to the corresponding 1,2-cis-isopropylidene-alpha-glycosides. Epoxidation of glycals with dimethyldioxirane followed by ZnCl(2)-catalyzed addition of acetone converted a variety of protected glycals into 1,2-cis-isopropylidene-alpha-glycosides in good yield. The reaction is compatible with a range of protecting groups, including esters, benzyl ethers, and silyl ethers, as well as free hydroxyl groups. This method has been applied to develop a synthesis of protected glucuronic acid 1, a key intermediate in the synthesis of glycosaminoglycans. Compound 1 was produced in seven steps and 32% overall yield.     

Synthèses dans la série des bis-indéno-anthracènes,I Le tétraoxo-5, 10, 15, 16-tétrahydro-5, 10, 15, 16-bis-indéno [2.1-a; 2′.1′-c] anthracène et le dihydro-5, 16-bis-indéno [2.1-a; 2′.1′-c] anthracène

Starting from 5-carboxy-6-methyl-7, 12-dioxo-7, 12-dihydro-indeno [1.2-a] fluorene (phthalacone-carboxylic acid) the first title compound, XI, has been synthesized in 4 steps (overall yield 28%). By anindependent way the corresponding hydrocarbon (second title compound, IV) has been obtained in 3 steps (overall yield 35%) starting from 2, 3′-bi-indenyle and 1, 4-naphthoquinone.     

Facile preparation of N-protected 2-alkylidene-1,3-imidazolidines

Stereoselective preparation of unsymmetrically protected 2-alkylidene-1,3-imidazolidines was achieved by the reaction of N,N′-protected ethylenediamine, bromopropynamide, and K₃PO₄ in hot DMF. When N-protected aminoethanol was used in place of the protected ethylenediamine, an oxazolidine derivative was produced.     

A short route to l-iduronic acid building blocks for the syntheses of heparin-like disaccharides

The effective preparation of differentially protected l-iduronic acid derivatives, as building blocks for the synthesis of heparin-like oligosaccharides, is described in less than nine steps starting from readily available 1,2-O-isopropylidene-6,3-d-glucuronolactone. The pivaloyl group was used as a permanent protecting group of hydroxyl groups. Two heparin-like disaccharides with different sulfation pattern have been prepared by using these l-iduronic acid building blocks.     

An investigation of some base induced transformations of the 1,4-benzodioxan ring system

The reaction between benzodioxan-2-carboxylic acid and ethylenediamine has been examined and related base induced transformations investigated.     

Efficient Synthesis of Biologically Active (±)‐Confluentin and (±)‐Daurichromenic Acid

One‐step synthesis of biologically active (±)‐confluentin is described from commercially available orcinol with trans,trans‐farnesal in the presence of ethylenediamine diacetate as a catalyst. Further conversion of synthetic confluentin to highly potent anti‐HIV agent, (±)‐daurichromenic acid, is accomplished by formylation and oxidation in two steps.     

Utility of dast (diethylaminosulfur trifluoride) in the chemistry of carbohydrates: synthesis of 3,4,6-trideoxy-3,4,6-triflouro-α-D-galactopyranosyl fluoride

The tetrafluorogalactose derivative $\text{6}$ has been synthesized in five steps starting from a protected allose precursor.     

Synthesis of 2-amino-8-oxodecanoic acids (Aodas) present in natural hystone deacetylase inhibitors

[reaction: see text] Differently substituted 2-amino-8-oxodecanoic acids (Aodas), present in naturally occurring inhibitors of hystone deacetylase (HDAC), have been prepared using a convergent approach. The configuration in position 2 was derived from enantiomerically pure allylglycine or glutamic acid, whereas the stereochemistry of the substituent in position 9 derived from lactic acid or glyceraldehyde derivatives. Starting from allylglycine, (S)-Aodas, protected at the nitrogen as Boc or Fmoc, were obtained in four steps in about 30% overall yield. These products have been used to prepare a simplified analogue of a natural cyclic tetrapeptide HDAC inhibitor by SPPS.     

Formic acid self-poisoning on bismuth-modified Pt(755) and Pt(775) electrodes

This paper reports the effect of bismuth on the formation of CO from formic acid on platinum stepped surfaces containing six atoms wide (111) terraces and monoatomic steps having (110) or (100) symmetry. In both cases the steps were elaborated by irreversibly adsorbed bismuth in such a way that CO should be produced on the remaining terrace sites. It was found that bismuth decoration of (100) steps causes a large decrease in CO formation, whereas the effect of the same adatom when adsorbed on (110) steps is almost negligible. In this latter case it is necessary to adsorb bismuth on the terrace sites in order to obtain a similar inhibition of the poisoning reaction.     

Synthesis of methyl N-Boc-(2S,4R)-4-methylpipecolate

An efficient stereoselective synthesis of fully protected (2S,4R)-4-methylpipecolic acid has been developed. The synthesis was achieved by initial asymmetric α-alkylation of glycine with a chiral iodide, affording the linear precursor as a single stereoisomer. Subsequent aldehyde formation using OsO(4)/NaIO(4) followed by immediate intramolecular cyclization afforded an enamine that was then subjected to hydrogenation to give the final compound in 23% yield over 10 steps.     

A convenient approach to total synthesis of synargentolide-B from l-ascorbic acid and d-ribose

A convenient and practical approach for the total synthesis of naturally occurring lactone synargentolide-B has been accomplished in 14 steps from the commercially available l-ascorbic acid and d-ribose involving Bestmann–Ohira reaction, zinc mediated allylation, ring closing-metathesis, and cross-metathesis reactions. The highlight of our strategy describes a one-pot reaction involving stereoselective addition of allylzinc reagent and selective reduction of terminal alkyne to obtain the key advanced intermediates.