光と酸素を活用する簡便な酸化プロセスの開発に関する研究

酸化反応は有機合成における最も重要な柱の一つである。しかしながら、従来の酸化反応は重金属を大量に使用しなければならない、廃棄物が大量に副生するなどの問題点を有しており、いわゆる“グリーンケミストリー”の概念に必ずしもそぐわないものがほとんどであった。一方、最近では安価で原子効率が高い分子状酸素を酸化剤として用いた触媒的酸化反応が報告されている。この方法は適当な触媒を用いた場合に、反応後に副生されるものが理論的に水のみであり、理想の酸化反応として注目を集めている。係る背景において、筆者らは分子状酸素を用いる酸化反応について研究を行い、紫外光照射下（400 nm）でも同様の酸化反応が進行することも見出した。さらに、上記の光酸素酸化反応を連続するエステル化反応へ展開し、芳香環上メチル基から芳香族カルボン酸エステルへの効率的な直接一段階合成法を確立することにも成功した。Oxidation is a very important transformation in organic synthesis; however, hitherto these methods usually involve the use of large quantities of heavy metals, which generate a large amount of waste, and are detrimental to the environment. On the other hand, recently, many researchers have reported catalytic oxidation processes with molecular oxygen, which generate little waste. Molecular oxygen has received a great deal of attention as an ideal oxidant, since it theoretically produces only water as the end product with a certain suitable catalyst is inexpensive and has higher atom efficiency than that of other oxidants.With this perspective, we have studied the oxidation with molecular oxygen, and developed the oxidation of methyl aromatics and alcohols to the corresponding carboxylic groups in the presence of a catalytic amount of bromine sources such as aq. HBr and Br2 under UV irradiation (400 nm). Moreover, in developing the above-mentioned oxidation following esterification, we accomplished efficient direct aerobic photooxidative synthesis of aromatic methyl esters from methyl aromatics

Asymmetric Conjugate Addition of α‑Cyanoketones to Enones Using Diaminomethylenemalononitrile Organocatalyst

A diaminomethylenemalononitrile organocatalyst efficiently catalyzed the asymmetric conjugate addition of α-cyanoketones to vinyl ketones to give the corresponding 1,5-dicarbonyl compounds, which bear an all-carbon quaternary stereogenic center with high enantioselectivities. This report is the first example of the asymmetric conjugate addition of α-cyanoketones to vinyl ketones using an organocatalyst

Perfluoroalkanesulfonamide Organocatalysts for Asymmetric Conjugate Additions of Branched Aldehydes to Vinyl Sulfones

Asymmetric conjugate additions of branched aldehydes to vinyl sulfones promoted by sulfonamide organocatalyst 6 or 7 have been developed, allowing facile synthesis of the corresponding adducts with all-carbon quaternary stereocenters in excellent yields with up to 95% ee

Asymmetric Conjugate Addition of Nitroalkanes to Enones Using a Sulfonamide–Thiourea Organocatalyst

The asymmetric conjugate addition of nitroalkanes to α,β-unsaturated ketones in the presence of a catalytic amount of a novel sulfonamide–thiourea organocatalyst resulted in the corresponding γ-nitro carbonyl products in high yields with excellent enantioselectivities (up to 97% ee)

Recombinant angiopoietin-1 restores higher-order architecture of growing blood vessels in mice in the absence of mural cells

Interactions between endothelial cells (ECs) and perivascular mural cells (MCs) via signaling molecules or physical contacts are implicated both in vascular remodeling and maintenance of vascular integrity. However, it remains unclear how MCs regulate the morphogenic activity of ECs to form an organized vascular architecture, comprising distinct artery, vein, and capillary, from a simple mesh-like network. A clear elucidation of this question requires an experimental model system in which ECs are separated from MCs and yet form vascular structures. Here we report that injection of an antagonistic mAb against PDGFR-β into murine neonates provides such an experimental system in the retina by completely blocking MC recruitment to developing vessels. While a vascular network was formed even in the absence of MCs, it was poorly remodeled and leaky. Using this vascular system ideal for direct assessment of the activities of MC-derived molecules, we show that addition of recombinant modified angiopoietin-1 restored a hierarchical vasculature, and also rescued retinal edema and hemorrhage in the complete absence of MCs. These observations demonstrate the potential of Ang1 as a new therapeutic modality for MC dropout in diseases such as diabetic retinopathies