Efficient synthesis of optically active atropisomeric anilides through catalytic asymmetric N-arylation reaction

In the presence of (R)-DTBM-SEGPHOS-Pd(OAc)2 catalyst, N-arylation of ortho-tert-butyl-NH-anilides with 4-nitroiodobenzene proceeds with high enantioselectivity (89-95% ee) to give optically active atropisomeric anilides possessing N-C chiral axis. Furthermore, the intramolecular version of the present catalytic asymmetric N-arylation gave atropisomeric lactams with high optical purity (94-96% ee).     

Structure,Properties and Biodegradation of Some Bacterial Copoly(hydroxyalkanoate)s

This article describes the relationships between not only comonomer-unit compositions but also their distributions and structures as well as properties for bacterial copoly(hydroxyalkanoate)s, including poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxy-propionate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxy-butyrate-co-4-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-mercapto-propionate). It was found that as-produced copoly(hydroxy-alkanoate)s have broad comonomer-unit compositional distributions, which we can control to some degree. The structure and properties of copoly(hydroxy-alkanoate)s depend not only on the chemical structure and the comonomer-unit composition but also on the comonomer-unit compositional distribution.     

Facile preparation of organozinc bromides using electrogenerated highly reactive zinc and its use in cross-coupling reaction

Highly reactive zinc was readily prepared by electrolysis of a DMF solution containing pyrene as a mediator with a platinum cathode and a zinc anode. Preferential reduction of pyrene occurred to generate the corresponding radical anion, which reduced zinc ions generated from anodic dissolution to give zero valent zinc with high reactivity. The reactive zinc was successfully used for an efficient transformation of bromoalkanes into the corresponding organozinc bromides. Organozinc bromides obtained were further used successfully in Pd-catalyzed cross-coupling reaction with various aryl iodides and bromides.     

Multiplex amplified product-length polymorphism analysis of 36 mitochondrial single-nucleotide polymorphisms for haplogrouping of East Asian populations

We present a reliable, rapid, and economical multiplex amplified product-length polymorphism (APLP) method for analyzing the haplogroup-diagnostic mitochondrial single-nucleotide polymorphisms (mtSNPs) in East Asian populations. By examining only 36 haplogroup-specific mtSNPs in the coding region by using four 9-multiplex polymerase chain reaction (PCR) and subsequent electrophoresis, we could safely assign 1815 individuals from 8 populations of Japanese, Korean, Chinese, and Germans to 45 relevant haplogroups. This multiplex APLP analysis of coding-region mtSNPs for haplogrouping is especially useful not only for molecular phylogenetic studies but also for large-scale association studies due to its rapid and economical nature. This is the first panel of mtSNPs in the coding region to be used for haplogrouping of East Asian populations.     

New synthetic method to 1,2-benzisothiazoline-3-one- 1,1-dioxides and 1,2-benzisothiazoline-3-one-1-oxides from N-alkyl(o-methyl) arenesulfonamides

Various N-alkylsaccharins were easily prepared in moderate to good yields by the reaction of N-alkyl(o-methyl)arenesulfonamides with (diacetoxyiodo)benzene in the presence of iodine under irradiation with a tungsten lamp (W-hν). On the other hand, irradiation of N-alkyl(o- methyl)arenesulfonamide derivatives bearing various subslituents on the aromatic ring with a high- pressure mercury lamp (Hg-hν), in the presence of (diacetoxyiodo)benzene and iodine gave the corresponding N-alkyl-1,2-benzisothiazoline-3-one-1-oxide derivatives in moderate yields, together with N-alkyl-1,2-benzisothiazoline-3-one-1,1-dioxide (saccharin) derivatives.     

Action Spectrum for the Photophobic Response of Ciona intestinalis (Ascidieacea, Urochordata) Larvae Implicates Retinal Protein

Ascidian tadpole larvae change swimming behavior during the course of development. The photic behavior of the larvae of Ciona intestinalis was monitored by a computerized cell-tracking system with a time resolution of 0.1 s. Newly hatched larvae swim at an average speed of 1.4 mm/s but show no response to light stimuli. The swimming speed of the larvae became slower (0.4 mm/s) 3 h after hatching and they were induced to swim more rapidly by a sudden decrease in light intensity 4 h after hatching. During the course of development, the maximal speed of swimming behavior increased with time until 8 h after hatching and then plateaued. The action spectrum for the step-down photophobic response of the larvae was determined at around 8 h after hatching and was fitted to Dartnall's nomogram with the absorbance maximum of the pigment located at 505 nm. These results suggest retinal proteins in the ocellus of the larvae are the photoreceptors for the photobehavior.     

The development of an automated continuous measurement system for the monitoring of HCHO and CH3CHO in the atmosphere by using an annular diffusion scrubber coupled to HPLC

An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH₃CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-performance liquid chromatograph (HPLC). With this technique, atmospheric HCHO and CH₃CHO were effectively collected by the annular diffusion scrubber which consists of a porous polytetrafluoroethylene (PTFE) tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine (DNPH) was selected as the scrubbing solution for collecting HCHO and CH₃CHO, which are derivatized to 2,4-dinitrophenylhydrazone-formaldehyde (DNPH-HCHO) and 2,4-dinitrophenylhydrazone-acetaldehyde (DNPH-CH₃CHO), respectively. An aliquot of the sample solution was automatically injected into an HPLC equipped with a semi-micro ODS column and a UV-VIS detector for separating and determining DNPH-HCHO and DNPH-CH₃CHO. All the operations are sequenced by a programmable controller, and automated continuous measurements are performed with a typical temporal resolution of 1 h. The collection efficiencies of HCHO and CH₃CHO were about 97% and 93%, respectively, at an air flow rate of 0.2 L/min. The lower detection limits (3σ of the blank hydrazones) of HCHO and CH₃CHO were 0.05 ppbv and 0.10 ppbv, respectively, in the case of 12-L air sample volume. Analytical response of a standard solution of DNPH-HCHO and DNPH-CH₃CHO by the HPLC during a 10-day continuous measurement was unchanged and the relative standard deviation (RSD) was < 1.0%. Interferences from O₃ and NO₂ were insignificant in this annular diffusion scrubber method. Both for HCHO and CH₃CHO measurements, concentrations from this developed system well agreed with those measured by a DNPH Silica cartridge method. Received: 15 July 1998 / Revised: 5 October 1998 / Accepted: 7 October 1998