Stereospecific radical polymerization

Radical polymerization of N-methyl-N-(2-pyridyl)acrylamide (MPyAAm) was carried out in dichloromethane at low temperatures in the presence of trifluoroacetic acid (TFA). The m dyad contents of the polymers obtained at 0°C increased linearly from 37% to 60% with increase in the [TFA]0/[MPyAAm]0 ratio from unity to 5. NMR analysis of MPyAAm-TFA mixtures in dichloromethane-d2 revealed that the favorable conformation in terms of the pyridyl group to the carbonyl group in MPyAAm switched from s-trans to s-cis by protonation. The results suggest that controlling the conformation of MPyAAm resulted in control of the stereospecificity in radical polymerization of the monomer

Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates

A palladium-catalyzed intramolecular Mizoroki-Heck-type reaction of diarylmethyl tert-butyl carbonates has been developed. The reaction proceeds under external base-free, neutral conditions to form the corresponding methyleneindanes in good yields only with liberation of CO2 and tBuOH. The resulting exo-methylene moiety is reactive and thus a good synthetic handle for further manipulations. Additionally, the asymmetric synthesis is also possible through a Pd/chiral Mandyphos ligand-mediated kinetic resolution. To the best of our knowledge, this is the first successful example of catalytic enantioselective Mizoroki-Heck-type reaction of secondary benzyl electrophiles. (Figure presented.).This is the accepted version of the following article: Matsude A., Hirano K., Miura M.. Palladium-Catalyzed Intramolecular Mizoroki-Heck-Type Reaction of Diarylmethyl Carbonates. Advanced Synthesis and Catalysis 362, 518 (2020), which has been published in final form at https://doi.org/10.1002/adsc.201901398. This article may be used for non-commercialpurposes in accordance with the Wiley Self-ArchivingPolicy [https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html

Highly Stereoselective Synthesis of 1,2-Disubstituted Indanes by Pd-Catalyzed Heck/Suzuki Sequence of Diarylmethyl Carbonates

A palladium-catalyzed Mizoroki-Heck-type cyclization/Suzuki-Miyaura cross-coupling cascade of diarylmethyl carbonates with arylboronic acid derivatives has been developed to deliver the corresponding 1,2-disubstituted indanes in good yields with high diastereoselectivity (trans/cis > 20:1). The key to achieve the high chemoselectivity and stereoselectivity is the use of the tris[3,5-di(tert-butyl)-4-methoxyphenyl]phosphine (DTBMP) ligand of remote steric hindrance. Moreover, the asymmetric synthesis is possible by the enantiospecific, stereoinvertive reaction of the optically active starting substrates to form the chiral indanes with high stereochemical fidelity (>98% es).Matsude A., Hirano K., Miura M.. Highly Stereoselective Synthesis of 1,2-Disubstituted Indanes by Pd-Catalyzed Heck/Suzuki Sequence of Diarylmethyl Carbonates. Organic Letters. 22(8), 3190-3194, (2020), 17 April 2020; © 2020 American Chemical Society. https://doi.org/10.1021/acs.orglett.0c00945

STEREOSPECIFIC RADICAL POLYMERIZATION

Radical polymerization of N-methylacrylamide (NMAAm), N,N-dimethylacrylamide (DMAAm), and N-methyl-N-phenylacrylamide (MPhAAm) was investigated in toluene at low temperatures. Atactic, isotactic, and syndiotactic polymers were obtained by the polymerization of NMAAm, DMAAm, and MPhAAm, respectively, indicating that the stereospecificity of the radical polymerization of acrylamide derivatives depended on the N-substituents of the monomer used. From the viewpoint of monomer structure, the origin of the stereospecificity of radical polymerization of NMAAm derivatives is discussed

FACTORS ASSOCIATED WITH DECELERATION OF RUNNING VELOCITY IN THE LAST PHASE OF THE 400-M SPRINT BASED ON KINETICS CHANGES

The purpose of this study was to investiThe purpose of this study was to investigate the factors associated with deceleration of running velocity during the 400-m sprint (at the 350-m point) based on kinetics changes. Fourteen male collegiate sprinters performed the 400-m sprint (50.26 ± 2.27 s) at a subjective effort level of 100%. The ground reaction force (1000 Hz) was measured 350 m from the start point, and running movements were recorded from the side by a high-speed camera (300 Hz). The results were as follows: 1) High running velocity was associated with a high stride length. 2) A statistically significant positive correlation was observed between the stride length and the angular impulse of hip flexion in the second half of the support phase. These results suggest that the angular impulse of hip flexion is higher, the leg which has been supported is being swung out forward greatly after ground release

Effect of a combination of hexamethylphosphoramide and alkyl alcohol on the stereospecificity of radical polymerization of N-isopropylacrylamide

Radical polymerization of N-isopropylacrylamide (NIPAAm) was investigated at low temperatures in the presence of both hexamethylphosphoramide (HMPA) and alkyl alcohols. Although HMPA and alkyl alcohols separately induced syndiotactic specificity in NIPAAm polymerization in toluene at low temperatures, a combination of HMPA and less bulky alkyl alcohols, such as methanol and ethanol, was found to induce isotactic specificity at –80°C. NMR analysis of mixtures of NIPAAm, ethanol and HMPA suggested the formation of a 1:1:1 complex through O–H•••O=C and N–H•••O=P hydrogen bonding. It is believed that the steric effect of HMPA enhanced by cooperative hydrogen bonding was responsible for the combined effect of HMPA and alkyl alcohols in inducing isotactic specificity

Implementation of RLS-based Adaptive Filterson nVIDIA GeForce Graphics Processing Unit

This paper presents efficient implementa- tion of RLS-based adaptive filters with a large number of taps on nVIDIA GeForce graphics processing unit (GPU) and CUDA software development environment. Modification of the order and the combination of calcu- lations reduces the number of accesses to slow off-chip memory. Assigning tasks into multiple threads also takes memory access order into account. For a 4096-tap case, a GPU program is almost three times faster than a CPU program

Efficient Implementation of RLS-Based Adaptive Filterson nVIDIA GeForce Graphics Processing Unit

This paper presents efficient implementa- tion of RLS-based adaptive filters with a large number of taps on nVIDIA GeForce graphics processing unit (GPU) and CUDA software development environment. Modification of the order and the combination of calcu- lations reduces the number of accesses to slow off-chip memory. Assigning tasks into multiple threads also takes memory access order into account. Multiple shader pro- cessor arrays are used to handle a large matrix. For a 8192-tap case, a GPU program is almost 30-times faster than a CPU program. Real-time processing is possible for an 8kHz-sampling and 512-tap case by us- ing 32 shader processors, which is only 25% of GeForce 8800GTS

Computationally efficient implementation of sarse-tap FIR adaptive filters with tap-position control on intel IA-32 processors

金沢大学理工研究域　電子情報学