Pt(II)- or Au(III)-catalyzed [3+2] cycloaddition of metal-containing azomethine ylides: highly efficient synthesis of the mitosene skeleton

[reaction: see text] Only 1-3 mol % of PtCl(2) or AuBr(3) was sufficient to promote generation and [3+2] cycloaddition of transition-metal-containing azomethine ylides derived from N-(o-alkynylphenyl)imines bearing an internal alkyne moiety. A highly efficient method for the preparation of synthetically useful tricyclic indole derivatives having a substituent at the 3-position of the indole nucleus was established by this method.     

Total Synthesis of Proposed Structure of Yuremamine and All Diastereomers Using [3+2]‐Cycloaddition of Platinum‐Containing Azomethine Ylide

Total synthesis of the proposed structure of yuremamine has been achieved for the first time based on the intermolecular [3+2]‐cycloaddition reaction of the platinum‐containing azomethine ylide. All the possible diastereomers of yuremamine were also synthesized via the common intermediate. Through these syntheses, it was confirmed that the proposed structure of yuremamine and the diastereomers differ from the natural product.     

Observation of nonlinear coupling between small-poloidal wave-number potential fluctuations and turbulent potential fluctuations in Ohmically heated plasmas in the JFT-2M tokamak

Two types of electrostatic modes with small-poloidal wave numbers (approximately 1 and 10-15 kHz) are observed in the edge region of Ohmically heated plasmas in the JFT-2M tokamak. The envelope of the higher frequency coherent mode is modulated at the frequency of the lower frequency mode. A bispectral analysis revealed that a significant nonlinear coupling among the two types of fluctuations and the broadband background turbulent potential fluctuations occurs inside the last closed magnetic flux surface, suggesting that a nonlinear process such as the parametric-modulational instability is involved.     

Platinum(II)-catalyzed generation and [3+2] cycloaddition reaction of α,β-unsaturated carbene complex intermediates for the preparation of polycyclic compounds

Pt(II)-catalyzed generation of unsaturated carbene complex intermediates from various propargyl ether derivatives based on electrophilic activation of alkynes was realized. These in situ generated unsaturated carbene complexes undergo [3+2] cycloaddition reaction with various vinyl ethers, leading to efficient formation of indoles, naphthols, and benzofuran fused with a five-membered ring in high yields.     

Photochemically promoted transition metal-free cross-coupling of acylsilanes with organoboronic esters

Intermolecular carbon-carbon bond formation between acylsilanes and organoboronic esters was achieved by photoirradiation under almost neutral, transition metal-free conditions. In this reaction, siloxycarbenes generated by photoisomerization of acylsilanes reacted with boronic esters to give the formal B-C bond insertion intermediates, which underwent unique rearrangement to afford the cyclic α-alkoxyboronic esters. Acidic treatment of the resulting crude products under air furnished the cross-coupled ketones in good yields.     

Synthesis of a novel water‐soluble NMDA receptor antagonist

A novel water‐soluble N‐methyl‐D‐aspartate (NMDA) receptor antagonist ATGDMAP 1 as synthesized and the effect of 1 on NMDA receptors was studied using voltage‐clamp recordings of recombinant NMDA receptors expressed in Xenopus oocytes. The compound 1 inhibited macroscopic currents in NR1/NR2A, NR1/NR2B, NR1/NR2C and NR1/NR2D receptor subtypes in oocytes voltage‐clamped at ‐70 mV. Mutant NR1/NR2B receptors containing NR1(T648A) or NR1(T648S) had very large holding currents when voltage‐clamped at ‐70 mV compared to that of wild‐type NMDA receptors, because these mutants generate constitutively open channels. ATGDMAP 1 and Mg²⁺, a channel blocker of the NMDA receptor, reduced the large holding currents needed for mutant NMDA receptors. These data indicate that ATGDMAP 1 directly acts on the channel pores of the NMDA receptor.