Transformimidoylation of 1-(N-Alkyliminoformyl) Imidazole with Amino Acid

In our preceeding paper,¹ we described a new synthetic method of reactive 1-(N-alkyliminoformyl)azoles (1) and the transfer of formimidoyl group (transformimidoylation) of 1 with amine, alcohol and the so-called active methylene compounds.     

Facile deprotection of dithioacetals by using a novel 1,4-benzoquinone/cat. NaI system

The combination of 1,4-benzoquinone and a catalytic amount of NaI was found to be effective for the deprotection of dithioacetals. The reactions proceeded efficiently under mild, near-neutral reaction conditions, producing a wide range of aryl and alkyl aldehydes and ketones generally in high yields with good functional group compatibility. The method developed therefore represents a general, facile, and highly applicable approach for deprotecting dithioacetals.     

Near-Infrared Chemometric Approach to Exhaustive Analysis of Rice Straw Pretreated for Bioethanol Conversion

We report a simple analytical procedure combining near-infrared (NIR) spectroscopy with multivariate analysis to detect the saccharification efficiency of pretreated rice straw. Three types of sample preparation methods were tested to develop a powerful calibration model, with the disk sample used as the standard protocol. From the spectra dataset of NaOH-treated biomass, we obtained a good calibration for the saccharification ratio and some major structural components by partial least-squares regression. Adding dataset from hot water and dilute sulfuric acid pretreatments to NaOH sample dataset, an acceptable calibration model to predict the saccharification ratio as well as the glucose, xylose, and lignin contents was generated. NIR has a great potential for rapid screening of saccharification efficiency of pretreated biomass, which would allows us to control the quality of processing toward better bioethanol production.     

Nine New Norlabdane Diterpenoids from the Leaves of Austroeupatorium inulifolium

Nine new norlabdane diterpenoids were isolated from the leaves of Austroeupatorium inulifolium collected in Indonesia. All of them have an acyl‐furan unit connected to C(11), and oxygenated functions at C(2) and C(3). The structure elucidations and the assignment of the absolute configurations of the isolated natural products were carried out by extensive spectroscopic analysis and the extended Mosher method, as well as chemical correlations. Antimicrobial activities and cytotoxicity against HL‐60 cells were determined using bioassays.     

Sequential one-pot glycosylation with glycosyl N-trichloroacetylcarbamate and trichloroacetate including dehydrative approach using 1-hydroxy sugars

An efficient sequential one-pot glycosylation has been developed with glycosyl trichlorocarbamate and trichloroacetate activated by the same Lewis acid and enabled by a change in reaction temperature. The αα-selective glycosylation was achieved using glucose, galactose, and mannose substrates after investigation into the reactivities of the two types of glycosyl donors. Sequential one-pot dehydrative glycosylation, including in situ preparation of glycosyl donors followed by generation of two glycosyl bonds, provided three types of trisaccharide.     

Synthesis of γ-amino alcohols from aldehydes, enamines, and trichlorosilane using Lewis base catalysts

The reaction of aldehydes, enamines, and trichlorosilane in the presence of a Lewis base catalyst, particularly N-methylpyrrolidinone and DMF, affords γ-amino alcohols with a high diastereoselectivity. The method consists of C-C bond formation between an aldehyde and an enamine, and a subsequent intramolecular reduction of the resulting iminium ion intermediate. In most cases, one diastereomer is exclusively generated, and we propose a transition state model for the intramolecular reduction of the iminium ion intermediate. Enamines, prepared beforehand from the corresponding ketone and amine, can be used in the reaction without purification. Furthermore, enantioselective catalysis using a chiral Lewis base catalyst is possible, although the enantioselectivity is modest. The current tandem method offers the first, concise synthetic method of γ-amino alcohols from aldehydes and enamines.     

Synthesis of resorcin[4]arene bearing self-folding substituent

Thiomethylation of resorcin[4]arene using N,N-diisopropyl-2-aminoethanethiol hydrochloride and formaldehyde [1:4:4 molar ratio] carried out in methanol/acetic acid [1:1 v/v] at 60 °C produced monofunctionalized product 3 in 68% yield. The introduced substituent was intramolecularly self-included into the cavity. This self-inclusion reduced the reactivity of the aromatic rings and inhibited further functionalization.     

Preparation of hybrid film of polyaniline and organically pillared zirconium phosphate nanosheet by electrodeposition

α-Zirconium phosphate was chemically modified with 1,2-bis(dimethylchlorosilyl)ethane to graft organic chain, and then it was used as host material for inorganic nanosheet-polyaniline hybrid. The grafted α-zirconium phosphate was exfoliated in an acetonitrile solution with tetrabutylammonium salt and aniline. The electrodeposition in the presence of aniline was performed, and then it resulted in a formation of higher-order structure in which phosphate nanosheet was propped up by 1,2-bis(dimethylchlorosilyl)ethane with intrusion of polyaniline into the nanospace. The gravimetric capacitance of the α-zirconium phosphate without grafts and polyaniline hybrid film was around 194 F/g with the base on the amount of polyaniline mass. On the other hand, the α-zirconium phosphate nanosheet with grafts and polyaniline hybrid film provided larger capacitance of around 350 F/g in maximum. The nanospace formed by grafted phosphate nanosheet with 1,2-bis(dimethylchlorosilyl)ethane molecules gives increased amounts of polyaniline included and diffusion paths for ions.     

Enantioselective, biocatalytic reduction of 3-substituted cyclopentenones: application to the asymmetric synthesis of an hNK-1 receptor antagonist

A convergent and enantioselective route to the hNK-1 receptor antagonist (1) is described, which sets all six stereogenic centers with high diastereoselectivity and delivers 1 in only 11 steps and 23% overall yield. The process was enabled by the development of the enantioselective enzymatic reduction of 3-functionalized cyclopentenones and stereospecific Pd-catalyzed etherification coupling of fragments 6 and 7.     

Reliability evaluation of the design space of the granulation process of mefenamic acid tablets using a bootstrap resampling technique

The design space of the granulation process of mefenamic acid tablets, based on Box and Behnken design datasets, was described by a response surface method incorporating multivariate spline interpolation. The reliability of the optimal solutions and the acceptance ranges were evaluated by a bootstrap (BS) resampling technique. The distribution of the BS optimal solutions was almost symmetrical; however, several solutions, which were quite different from the original solution, were mixed. The reason for this problem was considered to be the mixing of the global and the local optima. Therefore, we applied self-organizing map (SOM) clustering for dividing data into several clusters and identified the cluster containing the global optima. The accuracy and reproducibility of the optimal solution in the cluster containing the optimal solution were quantitatively evaluated. In addition, the response surfaces modeled from all the BS datasets contained in the cluster were plotted into the same coordinates with the original response surface. The plots of BS optimal solutions were distributed around the original solution. Moreover, the average of all the BS response surfaces sufficiently corresponded with the original response surface. The conservative limits of the 95% confidence intervals of the acceptance ranges in three response variables could be calculated using the standard deviations of the BS response surfaces. Consequently, it was considered that a novel evaluation method based on BS resampling and SOM could be used for quantitatively evaluating the precision of the nonlinear response surface model.