Tomoyuki Saito

A convergent synthesis of the C1-C16 segment of goniodomin A via palladium-catalyzed organostannane-thioester coupling.

A convergent synthesis of the C1-C16 segment of goniodomin A, an actin-targeting marine polyether macrolide natural product, has been achieved via a 2-fold application of palladium-catalyzed organostannane-thioester coupling.

Toward the Total Synthesis of Goniodomin A, An Actin-Targeting Marine Polyether Macrolide: Convergent Synthesis of the C15−C36 Segment

Stereoselective convergent synthesis of the C15-C36 segment of goniodomin A, an actin-targeting marine polyether macrolide natural product, has been achieved. The present synthesis features palladium(0)-catalyzed, copper(I)-mediated Liebeskind-Srogl cross-coupling as the fragment assembly process.

Discrimination of new physics models with the International Linear Collider

The large hadron collider (LHC) is anticipated to provide signals of new physics at the TeV scale, which are likely to involve production of a WIMP dark matter candidate. The international linear collider (ILC) is to sort out these signals and lead us to some viable model of the new physics at the TeV scale. In this article, we discuss how the ILC can discriminate new physics models, taking the following three examples: the inert Higgs model, the supersymmetric model, and the littlest Higgs model with T-parity. These models predict dark matter particles with different spins, 0, 1/2, and 1, respectively, and hence comprise representative scenarios. Specifically, we focus on the pair production process, e+e- -> chi+chi- -> chi0chi0W+W-, where chi0 and chi+- are the WIMP dark matter and a new charged particle predicted in each of these models. We then evaluate how accurately the properties of these new particles can be determined at the ILC and demonstrate that the ILC is capable of identifying the spin of the new charged particle and discriminating these models.

Progress toward the Total Synthesis of Goniodomin A: Stereocontrolled, Convergent Synthesis of the C12–C36 Fragment

Goniodomin A is a marine polyether macrolide natural product isolated from the dinoflagellate Alexandrium hiranoi. In this paper, we report stereocontrolled, convergent synthesis of a fully functionalized C12-C36 fragment of goniodomin A. The synthesis of the C12-C25 vinylstannane involved a Wittig reaction and a reductive cycloetherification for the construction of the dihydropyran ring. The C26-C36 thioester was synthesized via a Nozaki-Hiyama-Kishi reaction of an aldehyde and an iodoalkyne, the former of which was easily prepared from (R)-malic acid as a chiral source by taking advantage of substrate-controlled diastereoselective reactions. Finally, a palladium-catalyzed coupling of the C12-C25 vinylstannane and the C26-C36 thioester completed the synthesis of the target compound.

Distributed MIMO network for 5G enhanced mobile broadband

One of important applications in 5G mobile communications is the enhanced mobile broadband (eMBB). A promising approach for achieving 5G eMBB under the limited radio bandwidth and energy is an introduction of a small-cell structured network. An advanced utilization of multi-input multi-output (MIMO) transmission is also another possible approach. First, the conceptual structure of distributed MIMO network is introduced. A number of distributed antennas (DAs) are deployed over a macro-cell area and they are connected to a macro-cell base station (MBS) via optical mobile fronthaul. Then, we present the recent advances in distributed MIMO cooperative transmission, i.e., space-time block coded transmit diversity (STBC-TD) for improving the link capacity of a macro-cell edge area, minimum mean square error multiuser multiplexing combined with singular value decomposition (MMSE-SVD) for increasing the sum capacity, and blind selective mapping (SLM) for reducing the transmit signal peak-to-average power ratio (PAPR).

Cooperative Distributed Antenna Transmissions

Distributed antenna small-cell network is a promising 5G network. In this paper, a comprehensive report of recent advance in the cooperative distributed antenna transmission (CDAT) is provided. Single-user space-time block coded transmit diversity (STBC-TD) and multi-user minimum mean square error filtering combined with singular value decomposition (MMSE-SVD) are presented. Also presented is blind selected mapping (blind SLM) which can suppress the peak-to-average signal power ratio (PAPR) and requires no side information transmission. The effectiveness of CDAT in the presence of co-channel interference (CCI) from adjacent macro- cells is confirmed by computer simulation.

MIMO channel estimation for time-division duplex distributed antenna cooperative transmission

We have been studying cooperative distributed antenna transmission (CDAT) as a promising technique for realizing the 5th generation (5G) high-speed mobile communications. Assuming time division duplex (TDD), the macro-cell base station (MBS) and the user equipments (UEs) conduct the channel estimation independently to obtain the shared channel state information (CSI). In this paper, we introduce a TDD frame structure consisting of uplink pilot time slot and downlink pilot time slot followed by data time slots. MIMO channel estimation is done before the user data transmission. Also presented is the pilot signal design. The accuracy of the proposed MIMO channel estimation and achievable bit error rate (BER) performance of user data transmission are evaluated by computer simulation.