Asymmetric reduction of benzil to (S)-benzoin with whole cells of Bacillus cereus

Benzil (1) was selectively reduced to (S)-benzoin (2) in the presence of a wild-type Bacillus cereus Tim-r01. A 92% yield of 2 with 94% enantiomeric excess ratio was attained in phosphate-buffered saline (PBS) (pH 7.5) by using glucose as a nutrient at 37 degrees C for 12 h. Compound 2 was not reduced further to hydrobenzoin (3) at all. The reduction activity differed greatly depending on the strain of B. cereus. Under these conditions the B. cereus strains IFO3001, IFO15305, IAM1110, IAM1229, IAM1656, and IAM1729 gave 2 in yields ranging from 23 to 46% and the configuration of 2 was (S)-form (7 to 86% ee).     

Head-to-tail dimerization of acrylates catalyzed by iridium complexes

Head-to-tail dimerizations of acrylates and vinyl ketone were successfully performed by the use of iridium complexes in good yields. An iridium hydride complex generated in situ from [IrCl(cod)]2 and alcohols in the presence of Na2CO3 and (MeO)3P was found to be an active species promoting the head-to-tail dimerization of acrylates. Thus, butyl acrylate afforded the corresponding head-to-tail dimer in 86% yield.     

Crystal and molecular structure of a new diterpenyl glycoside from Pteris cretica L.

The crystal and molecular structure of a new diterpenyl glycoside, Ptr-1, is presented. The crystal is triclinic, space group P1, with a = 8.2414(8) Å, b = 13.0826(9) Å, c = 6.1427(8) Å, = 95.345(9)°, = 111.589(8)°, = 96.726(7)°, V = 604.9(1) ų, Z = 1. The structure was solved by direct methods and refined by full-matrix least-squares methods to a final R = 0.049 (Rw = 0.099) for 1872 independent reflections. The molecular structure is based on a glycopyranosyl group and a tetracyclic group. The glycopyranosyl group is -D-allopyranosyl group. The tetracyclic group consists of 1 five-membered and 3 six-membered rings.     

Synthesis and properties of halogen- or methyl-containing poly(diphenylacetylene) membranes

Novel diphenylacetylenes with both trimethylsilyl groups and other substituents (R₂C₆H₃CCC₆H₄-p-SiMe₃, R = m,p-Cl,Cl, m,m-Cl,Cl, m,p-Br,Br, m,m-Br,Br, m,p-Me,Me, m,m-Me,Me, 1a–f, respectively) were polymerized with TaCl₅–n-Bu₄Sn to produce solvent-soluble polymers (2a–f). Most polymers (2a–e) had high molecular weight over 1 × 10⁶, and gave free-standing membranes by the solution casting method. Desilylation of these Si-containing polymer membranes was carried out with trifluoroacetic acid (TFA), which afforded solvent-insoluble desilylated polymer membranes (3a–e). According to thermogravimetric analysis (TGA), both Si-containing and desilylated polymers showed high thermal stability (T₀ ≥ 420 °C). The fractional free volume (FFV) of both Si-containing and desilylated polymer membranes (2a–d, 3a–d) were fairly large (ca. 0.27–0.32), while the FFVs of membranes (2e, 3e) were rather small (0.28 and 0.24). The oxygen permeability coefficients (P_O2) of 2a was as high as 5400 barrers, which is the largest among all the poly(diphenylacetylene) derivatives. Polymers 2b–d also exhibited high oxygen permeability, and their desilylated ones 3b–d retained similar high oxygen permeability. On the other hand, the P_O2 values of 2e and 3e were 1200 and 530 barrers, respectively, which are smaller than those of the halogen-containing polymers (2a–d and 3a–d).     

Synthesis of polyimide and poly(imide-benzoxazole) in polyphosphoric acid

A polyimide made from 4,4′-diaminodiphenyl ether (ODA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was synthesized in polyphosphoric acid. Although the polymerization proceeded heterogeneously, a polyimide with an inherent viscosity of 0.90 was obtained, and a tough and flexible film was made from this polyimide. This polymerization was a one-step reaction including polycondensation and imidization; this was also confirmed by a model reaction between aniline and phthalic anhydride. Utilizing this polymerization method, 3,3′-dihydroxy-4,4′-diaminobiphenyl and 2 mol of 4-aminobenzoic acid were reacted in PPA, then BPDA was reacted to obtain an alternate copolymer containing imide and oxazole rings. This reaction gave a homogeneous solution of the poly(imide-benzoxazole). © 1993 John Wiley & Sons, Inc.     

Studies on the terpenoids and related alicyclic compounds—XXII: Stereochemical study on the angular hydroxylation of polycyclic ketones using benzeneseleninic anhydride

Introduction of an OH group to the tertiary carbon of simple ketones (1, 2 and 6), furanoeremophilane-type ketones (12–19), and tricyclic ketones (20–22) by the use of benzeneseleninic anhydride is described. 10β-Hydroxy compounds were obtained in the case of 12–14 and 20–22. 10α-Hydroxy compounds were obtained in the case of 15 and 16. In the hydroxylation reaction of polycyclic ketones using benzeneseleninic anhydride, the results suggest that the thermodynamically more stable product was usually produced as the major product.     

Current levels and distribution of 137Cs and Pu isotopes in soil on the Kazakhstan territory of the Kazakhstan-Chinese border: Semipalatinsk and Lob Nor nuclear test sites detonation

More than 100 soil samples were collected from 46 sites along roads and some settlements connecting Alma-Ata to Semipalatinsk City of the Kazakhstan-Chinese border and analyzed for ¹³⁷Cs and Pu isotopes (²³⁸Pu, ²³⁹Pu and ²⁴⁰Pu). The mean ¹³⁷Cs inventory at each site was within the range of 1,000-3,000 Bq/m² for most of the sites. The ^239,240Pu concentration and its inventories were observed in the wide range of 0.18-2.6 Bq/kg and 28-677 Bq/m², respectively. At the most northern sites in the areas studied, higher^239,240Pu inventories were found corresponding to the increase of ^239,240Pu fraction which was not leached by hot digestion with conc. HNO₃+H₂O₂. The ^239,240Pu/¹³⁷Cs activity ratios for the soil samples from the southern areas lie in the narrow range of 0.016–0.039 (most of data being 0.02–0.03), probably indicative of global fallout origin. On the other hand, a little or several higher ratios (0.05 to 0.22) were found for soil samples from the northern areas. These higher ratios demonstrate strongly that there was additional Pu input of local fallout due to the atomic explosions. From ²⁴⁰Pu/²³⁹Pu atomic ratios measured, contribution of local fallout ^239,240Pu, probably from the SNTS, was found to be higher (60–86%) in the sites around the northern areas than the southern ones. The present data might serve not only as a current baseline information on distribution and contamination levels of the long-lived fallout radionuclides in the Kazakhstan areas of the Kazakhstan-Chinese border, but also as a aid of selection of control area for epidemiological projects.     

A contribution to the theory of OD EPR of spin-correlated radical pairs

A composite structure of OD EPR spectra is predicted. The OD EPR spectra consist of a broad component which manifests many features similar to conventional CW EPR spectra and a narrow component which appears as a hole in the broad spectrum. The width of the narrow component is estimated. The contribution of singlet-triplet dephasing to the shape of the OD EPR spectra is discussed comprehensively. It is shown that changes of the OD EPR spectra with an increase in the rate of singlet-triplet dephasing can be interpreted in terms of a redistribution of the populations of mixed (singlet and triplet) states of radical pairs and of exchange of the coherences corresponding to the EPR transitions for radical pairs.     

First Ritter-type reaction of alkylbenzenes using N-hydroxyphthalimide as a key catalyst

The first Ritter-type reaction of alkylbenzenes with nitriles has been successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. Thus, treatment of ethylbenzene with ammonium hexanitratocerate(IV) (CAN) in the presence of a catalytic amount of NHPI in EtCN under argon produced the corresponding amide in good selectivity.