Synthesis of polyhydroxylated bicyclic tetrahydrofurans and tetrahydropyrans via a stereoselective domino cyclization/reduction reaction

A novel reaction cascade involving a Lewis acid-induced migration of an isopropylidene protecting group followed by the formation of a pyranose or furanose ring and subsequent reduction of the hemiacetal is described. Depending on the reaction conditions, as well as, the stereochemistry of the substrate, polyhydroxylated tetrahydrofurans or tetrahydropyrans can be obtained in reasonable yields. The synthons used in this transformation were prepared via a highly stereoselective one-pot tandem reaction, consisting of a 1,4-Michael addition of vinylmagnesium bromide to d-glucose-derived cyclohexenone followed by aldol reaction with 2,3-O-isopropylidene-d-glyceraldehyde.     

Stereoselective synthesis of tacalcitol via (R)-MeCBS catalyzed borane reduction

A novel and efficient approach for the synthesis of 1α, 24(R)-dihydroxyvitamin D₃ (tacalcitol) starting from readily available enone 1 has been achieved with high stereoselectivity. The key step involved in the synthesis of tacalcitol was the stereoselective reduction of enone 1 using borane as the reducing agent, and the effects of the critical reaction parameters such as temperature, various borane complexes have been examined. Finally, tacalcitol was obtained in five steps from enone 1 with an overall yield of 32% and a ratio of 24-R/S = 95/5.     

Synthesis of 4H-1,3-benzoxazin-4-ones from 2,2-diazidobenzofuran-3(2H)-ones

Benzoxazine derivatives are useful building blocks and display various biological activities. We serendipitously discovered and subsequently developed a new one pot method for the synthesis of 2-(dimethyl amino)/2-morpholino/2- (piperidin-1-yl)-4H-benzo[e][1,3]oxazin-4-ones from corresponding substituted 2,2-diazidobenzofuran 3(2H) - ones and N-formyl dimethyl amine (DMF)/N-formylmorpholine/N-formylpiperidine using m-CPBA at 100?°C in moderate to good yields. We also demonstrated the utility of 4H-benzoxazines for the synthesis of other medicinally important compounds such as 2-hydroxyphenyl substituted 1,2,4-triazoles, unsymmetrical 1,3,5-triazines, and 1,2,4-oxadiazoles.     

Preparation of the diastereomerically pure 2S-hydroxy derivative of dihydrolevoglucosenone (cyrene)

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Paramagnetic Pd+ centers in the polymeric matrices of palladium(I) sorbates and 4-pentenate

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The reaction of 4-(1,3,2-benzodioxaphosphol-2-yloxy)-3-tert-butylpent-4-en-2-one with hexafluoroacetone

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Synthesis of cyclic norspermidine derivative of protohemin IX

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Photocatalytic properties of SnO2–SnO nanocomposite prepared via pulse alternating current synthesis

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Aza-Henry reaction with perfluoroalkylated cyclic ketimines

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Synthesis of enantiomerically pure 2-(N-aryl,N-alkyl-aminomethyl)aziridines: a new class of ligands for highly enantioselective asymmetric synthesis

A simple and effective synthesis of enantiomerically pure 2-(N-aryl-, N-alkyl-aminomethyl)aziridines from (2S)-N-tritylaziridine-2-carboxylic acid methyl ester has been developed. Treating of this key ester with several primary and secondary amines in the presence of AlMe₃ provided the corresponding chiral N-trityl-2-carboxamides, and their reduction performed with different reagents resulted in the formation of the expected 2-(aminomethyl)aziridines. The choice of reaction conditions allows to either keep or leave the trityl substituent in the product. Such 2-(aminoalkyl)aziridines have shown very high catalytic efficiency in the asymmetric arylation of aldehydes and in other testing asymmetric reactions. On the other hand, homochiral N-trityl-2-carboxamides are interesting building blocks for the synthesis of various biologically active compounds.     

The novel structural modification of pyridoxal via its cyclization into 2-acyl- and 2-heteroarylfuro[2,3-c]pyridines

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A highly stereoselective and efficient synthesis of enantiomerically pure sitagliptin

A highly stereoselective and efficient synthesis of sitagliptin 1 consisting of a chiral β-amino acid unit has been achieved through 6 steps from commercially available 2,4,5-trifluorobenzaldehyde 4. The chiral antidiabetic drug was obtained with almost perfect enantiomeric purity (>99.9% ee) in 40.9% overall yield. The key feature of the synthesis is the addition of a malonate enolate to a chiral sulfinylimine in more than 99:1 dr. Our synthetic procedure proved to be highly efficient, economical, and sustainable.     

3-(4-Phosphoryl-4-methyl-2-oxopentyl)-3-hydroxyindolin-2-ones,the first phosphorus analogues of natural convolutamydines

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Synthesis and photophysical studies of novel 4-aryl substituted 2-phenyl-, 2-(fluoren-2-yl)- and 2-cymantrenylquinazolines

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Silver-catalyzed diastereo- and enantioselective Michael additions of 2-oxazoline- and 2-thiazoline-4-carboxylate to nitroalkenes

The silver/ThioClickFerrophos (a chiral ferrocenyl P,S-ligand)-catalyzed Michael additions of 2-oxazoline- and thiazoline-4-carboxylate to nitroalkenes were highly anti-selective and enantioselective and produced the corresponding adducts in high yields.     

Synthesis,structure and magnetic properties of the dinuclear complex [1,3-C6H4{NC(Ph)N(SiMe3)}2]3Dy2 coordinated by ansa-bis(amidinate) ligands with a m-phenylene linker

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Microwave-assisted synthesis of 3-aminoarylquinolines from 2-nitrobenzaldehyde and indole via SnCl2-mediated reduction and facile indole ring opening

A simple and efficient one-pot two-step synthesis of substituted 3-aminoarylquinolines has been achieved from 2-nitrobenzaldehyde and indoles under microwave irradiation. Firstly 2-nitrobenzaldehydes is reduced to 2-aminobenzaldehyde in situ by commonly used chemo selective reductant SnCl₂ followed by condensation of indole. The acidic nature of the resultant reaction mixture due to SnCl₂ helps in the condensation and facile ring opening of indole leading to the formation of 3-aminoarylquinoline derivatives in good to moderate yields.     

Microwave-assisted direct esterification of a cyclic phosphinic acid with phenols

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Quantum chemical modeling of solid-state B4X structures containing tetrahedral B4 units with X = B,C, Al,Si

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Synthesis and photophysical studies of novel 2-[5-(4-diethylaminophenyl)thiophen-2-yl]quinazoline derivatives

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