Amino Amide Organocatalysts for Asymmetric Michael Addition of β-Keto Esters with β-Nitroolefins

Asymmetric Michael addition of β-keto esters with trans-β-nitroolefins using chiral amino amide organocatalyst was tried and afforded synthetically useful chiral Michael adducts in both excellent chemical yields (up to 99%) and stereoselectivities (up to dr. 99:1, up to 98% ee)

Hybrid-Type Squaramide-Fused Amino Alcohol Organocatalysts for Enantioselective Nitro-Aldol Reaction of Nitromethane with Isatins

A series of new hybrid type squaramide-fused amino alcohol (SFAA) catalysts were synthesized and their catalytic efficiency in enantioselective nitro-aldol reaction of various isatins with nitromethane that afford the chiral 3-substituted 3-hydroxyoxindoles in excellent chemical yields (up to 99%) and high enantioselectivities (up to 95% ee) is described. The resulting chiral 3-hydroxyoxindoles could be used as synthetic precursors for the synthesis of several natural products with a broad spectrum of fascinating biological activities

Cis and trans radicals generated in helical poly(propargyl acetate)s prepared using a [Rh(norbornadiene)Cl]2 catalyst

The poly(propargyl acetate) (A) having a helical cis–transoid structure was stereospecifically prepared using the Rh complex catalyst, [Rh(norbornadiene)Cl]2, in MeOH or NEt3 solvent at 0 and 40 °C in moderate yield. Electron spin resonance (ESR) analysis of the polymer revealed the formation of the cis (B) and trans (C) radicals which were produced through the thermal rotational scission of the helical cis CC bonds in the main-chain during the polymerization. The spatial and geometrical structure was successfully deduced using the two analogues’ polymers in which either methyl or methylene group is deuterated, by the aide of computer simulation of the observed ESR spectra together with the calculation of spin density of the two radicals

Poly-3-hydroxybutyrate (PHB) production from alkylphenols, mono and poly-aromatic hydrocarbons using Bacillus sp. CYR1: A new strategy for wealth from waste

In the present study five different types of alkylphenols, each of the two different types of mono and poly-aromatic hydrocarbons were selected for degradation, and conversion into poly-3-hydroxybutyrate (PHB) using the Bacillus sp. CYR1. Strain CYR1 showed growth with various toxic organic compounds. Degradation pattern of all the organic compounds at 100 mg/l concentration with or without addition of tween-80 were analyzed using high pressure liquid chromatography (HPLC). Strain CYR1 showed good removal of compounds in the presence of tween-80 within 3 days, but it took 6 days without addition of tween-80. Strain CYR1 showed highest PHB production with phenol (51 ± 5%), naphthalene (42 ± 4%), 4-chlorophenol (32 ± 3%) and 4-nonylphenol (29 ± 3%). The functional groups, structure, and thermal properties of the produced PHB were analyzed. These results denoted that the strain Bacillus sp. CYR1 can be used for conversion of different toxic compounds persistent in wastewaters into useable biological polyesters

Chiral primary amino alcohol organobase catalyst for the asymmetric Diels-Alder reaction of anthrones with maleimides

Simple chiral TES-amino alcohol organocatalysts containing a bulkysilyl [triethylsilyl: TES] group on oxygen atom at γ-position were designed andsynthesized as new organocatalysts for the enantioselective Diels-Alder (DA) reactionof anthrones with maleimides to produce chiral hydroanthracene DA adducts (up to99% yield with up to 94% ee)

An efficient synthesis of chiral isoquinuclidines by Diels-Alder reaction using Lewis acid catalyst

The Diels-Alder reaction of 1,2-dihydropyridine derivatives (1-phenoxycarbonyl-1,2-dihydropyridine 1 or 1-methoxycarbonyl-1,2-dihydropyridine 4) with N-acryloyl (1S)-2,10-camphorsultam (1S)-2 (or N-acryloyl (1R)-2,10-camphorsultam (1R)-2) in the presence of Lewisacid such as titanium tetrachloride, zirconium tetrachloride, and hafnium tetrachloride afforded the endo-cycloaddition product, 2-azabicyclo[2.2.2]octane derivatives in good yields with excellent diastereoselectivity. The absolute stereochemistry assignment of the endo-cycloaddition product (1S)-5a starting from N-acryloyl (1S)-2,10-camphorsultam (1S)-2hasbeen established to be (1S, 4R, 7S) and the reaction mechanism was proposed

Lipase-catalyzed domino Michael-aldol reaction of 2-methyl-1,3-cycloalkanedione and methyl vinyl ketone for the synthesis of bicyclic compounds

Synthesis of bicyclic compounds was achieved via a lipase-catalyzed, stereoselective, domino Michael–aldol reaction of 2-methyl-1,3-cycloalkanedione and methyl vinyl ketone. Appropriate reaction conditions, including the type of enzyme, solvent, and temperature, were determined. In addition, the effects of solvent polarity and addtives were investigated. The reaction proceeded in the presence of lipase AS in a solution of 20% acetone in dimethylsulfoxide (DMSO) at 10 °C for 8 days, followed by the addition of p-toluenesulfonic acid (TsOH) to afford bicyclic compounds in 51–83% yields with moderate stereoselectivity. Although this domino Michael–aldol reaction showed only moderate stereoselectivity, even with the acid-supported enhancement of the reaction, these results represent potential new applications for lipase

A novel chiral oxazolidine organocatalyst for the synthesis of an oseltamivir intermediate using a highly enantioselective Diels-Alder reaction of 1,2-dihydropyridine

Enantioselective Diels-Alder reactions of 1,2-dihydropyridines with acroleins using a novel chiral oxazolidine organocatalyst afforded chiral isoquinuclidines that is an efficient synthetic intermediate of oseltamivir, with fairly good chemical yield and excellent enantioselectivity (90%, up to >99% ee)

New Hybrid-type Squaramide-Fused Amino Alcohol Organocatalyst for Enantioselective Domino Michael Addition/Cyclization Reaction of Oxoindolines with Cyclic 1,3-Diketones

The new hybrid-type squaramide-fused amino alcohol containing both a Bronsted basic site and hydrogen bondingsites in the molecule showed a high catalytic activity as an l organocatalyst in the enantioselective domino Michael addition/cyclization reaction of oxoindohnes with cyclic 1,3-etones to afford\u27the chiralsproonjugate oxindoles featuring 2-aminopyrans fusing with l carbo-heterocyclic ring systems with l excellent chemical yields (up Ito 98%) and enantioselectivities (up to 95% ee). The obtained chiral spiroconjugated 2-aminopyrans bearing quaternary stereogenic carbon center could be used as l synthetic precursors for several natural products that ave a broad spectrum Iof fascinating biological activities

Structure-activity relations of rosmarinic acid derivatives for the amyloid β aggregation inhibition and antioxidant properties

Amyloid-β aggregation inhibitors are expected to be therapeutic or prophylactic agents for Alzheimer\u27s disease. Rosmarinic acid, which is one of the main aggregation inhibitors derived from Lamiaceae, was employed as a lead compound and its 25 derivatives were synthesized. In this study,the structure-activity relations of rosmarinic acid derivatives for the amyloid-β aggregation inhibitory effect (MSHTS assay), antioxidant properties, and xanthine oxidase inhibition were evaluated. Among the tested compounds, compounds 16d and 19 were found to the most potent amyloid aggregation inhibitors. The SAR revealed that the necessity of the presence of the phenolic hydroxyl on one side of the molecule as well as the lipophilicity of the entire molecule. The importance of these structural properties was also supported by docking simulations