Synthesis of all four stereoisomers of 5-hydroxy-4-methyl-3-heptanone using plants and oyster mushrooms

All four possible stereoisomers of 5-hydroxy-4-methyl-3-heptanone were synthesized from common achiral reagents using fast, straightforward organic synthesis, including the use of whole tissue of Daucus carota, Solanum melongena, and Pleurotus ostreatus.     

A process for the rapid removal of dialkylamino-substituents from aromatic rings. Application to the expedient synthesis of (R)-tolterodine

A range of N,N-dialkylanilines have been successfully converted to the parent substituted benzenes by a novel two-step pathway. The products are obtained in good yields and optical purity of adjacent stereocenters is maintained. This technology has been applied toward the synthesis of (R)-tolterodine.     

A new, enantioselective synthesis of (+)-isolaurepan

A highly enantioselective synthesis of 2,6-syn-disubstituted tetrahydropyrans from commercially available tri-O-acetyl-d-glucal, based on a thermal Claisen rearrangement, allows enantioselective synthesis of (+)-isolaurepan when combined with a ring expansion reaction using trimethylsilyldiazomethane.     

Enantioselective epoxidation of 2-substituted 1,4-naphthoquinones using gem-dihydroperoxides

New gem-dihydroperoxides were successfully used for DBU-promoted enantioselective epoxidation of 2-substituted 1,4-naphthoquinones. The corresponding 1,4-naphthoquinone epoxides were obtained in yields up to 97% and ee’s up to 82%.     

New chiral (salen)manganese(III) systems for asymmetric epoxidation of styrene

Highly enantioselelctive and repeatable epoxidation of styrene was performed by using new chiral (salen)Mn(III) catalysts, which were derived from the initial immobilization of a homogeneous (salen)Mn(III) complex on solid carriers and subsequent dispersion into ionic liquids. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Solvent-free synthesis and properties of carboxymethyl starch fatty acid ester derivatives

Water-soluble, partially hydrophobized polysaccharides have become attractive due to their potential to act as polymeric surfactants. From carboxymethyl starch (CMS), water-soluble polymeric surfactants were prepared by esterification using two unconvential methods based on (A) a reaction with mixed anhydrides and (B) with methyl laureate (MELA) and methyl esters of the fatty acid complex of rape seed oil (MERO) under ‘solvent-free’ conditions. The obtained CMS derivatives were characterized by structural, surface-active and surfactant performance properties. Esterification using method B was successful in contrast to method A which yielded derivatives with a very low extent of esterification. Although the derivatives reduced the surface tension moderately, they exhibited remarkable emulsifying properties. The performance tests indicated good washing power and antiredeposition efficiency. The results suggest that suitable polymeric surfactants can be prepared by the unconventional esterification method B using both acylation agents. The preparations might substitute the expensive and invasive industrially applied conventional methods.     

Chiral salen Mn(III) complex-based enantioselective potentiometric sensor for l-mandelic acid

A new enantioselective potentiometric sensor containing chiral salen Mn(III) as the chiral selector was designed for the assay of l-mandelic acid (l-MA). Optimized membrane electrodes displayed linear dynamic range from 1 × 10⁻⁵ to 1 × 10⁻¹ mol L⁻¹ with a detection limit of 7.2 × 10⁻⁶ mol L⁻¹ and a Nernstian response of −58.1 ± 0.5 mV decade⁻¹ towards l-MA within pH range 7.0-10.2. The potentiometric enantioselectivity coefficient () of this sensor was −4.0, indicating that the chiral salen Mn(III) complex-based electrode exhibited fairly good discrimination toward l-MA over counter isomer d-MA. The mechanism of chiral recognition for l-MA is discussed by using HF/STO-3G calculation method simulation.     

疏水双功能介孔固体酸的合成及其在乙酸乙酯酯化反应中的应用

通过水热合成法一步合成了具有不同疏水基团－CH₃ 、－(CH₃)₂ 和－(CH₃)₃的双功能介孔固体酸SBA-15-SO₃H－(CH₃)_x催化剂。通过X射线粉末衍射(XRD)、N₂吸脱附、元素分析等方法对催化剂进行了表征,并在乙酸乙酯酯化反应中进行催化性能评价。结果表明,随着疏水前驱体中甲基数的增加,样品的疏水性增强。SBA-15-SO₃H-(CH₃)_x催化剂的催化活性随着疏水性的增强而提高,而具有较强疏水性的材料SBA-15-SO₃H-(CH₃)₃在反应中具有较高的催化性能。以SBA-15-SO₃H-(CH₃)₃为催化剂,酯化反应的最优条件为：温度为120℃,乙酸与乙醇摩尔比为4∶1,催化剂质量分数为1 %,反应时间为1h。在此条件下,乙醇的转化率和乙酸乙酯的选择性分别为93%和100%。     

3,5-二(吡啶-甲氧基)苯甲酸吡啶-甲基酯的合成

具有三脚架构型的多吡啶类化合物,因其具有众多的配位原子以及较为特殊的分子构型,在与金属离子配位的过程中,一方面可以通过吡啶氮的配位键、氢键、芳香环的π-π作用等方式构筑出结构新颖的配合物[1-4];另一方面因其具有三脚架的构型,其三条侧链可自由翻转形成大小合适的空腔,能够与不同的客体分子或离子结合,有可能筛选出在分子识别、分子交换、电子传递和选择性催化等方面具有特殊性能的功能材料[5-8].因此,合成具有三脚架构型的多吡啶类配体是这些配合物在诸多领域中应用的关键.     

Collision-induced dissociation of the negative ions of simvastatin hydroxy acid and related species

Simvastatin hydroxy acid (1) is a well-known, potent HMG-CoA reductase inhibitor for the treatment of hypercholesterolemia. Its lactone, simvastatin (commercial name Zocor) (a prodrug of 1), has been widely prescribed in the USA and throughout the world. In this work, collision-induced dissociation (CID) of the negative ion of 1 (m/z 435), a carboxylic anion, was analyzed in detail. The major fragmentation pathway of this ion is a novel de-esterification to form the negative product ions at m/z 319 and 115. The ion at m/z 319 undergoes further collision-induced rearrangements to form the negative ions at m/z 215, 159 and 85. Possible mechanisms of the de-esterification are discussed in terms of both charge-initiated and charge-remote fragmentations. The de-esterification of the negative ion of 1 and the rearrangements of the ion at m/z 319 are rationalized by charge transfer and negative-charge initiated fragmentation. This study deepens our understanding of collision-induced fragmentations of carboxylic anions with multi-functional groups. A comparison of the CID data for the negative ions of 1 and 5 (a major oxidation degradate of 1) indicates that the analysis of the CID data for 1 can serve as a basis for identification of oxidation degradation products or metabolites of 1. The analysis of the CID data for the negative ion of 1 also reveals the fundamental characteristics of the CID data for the negative ions of other statin hydroxy acids such as lovastatin (3) and pravastatin (4).