Yoshinari Sawama

Deuterium-labeled compounds are widely utilized in various scientific fields. Although the H–D exchange reaction is a straightforward method to produce the deuterated organic compounds, it requires expensive deuterium (D₂) gas and/or harsh reaction conditions in conventional methods. This Account summarizes platinum-group metal on carbon (e.g., Pd/C, Pt/C, Ru/C, Rh/C)-catalyzed efficient multi and/or site-selective H–D exchange methods of various compounds including bioactive molecule

The efficient and catalytic dehydrogenation of alcohols is a clean approach for preparing carbonyl compounds accompanied only by the generation of hydrogen gas. We have accomplished the heterogeneous rhodium-on-carbon catalyzed dehydrogenation of secondary, as well as primary, alcohols to the corresponding ketones and carboxylic acids in water under basic conditions.

Abstract The catalytic dehydrogenation of alcohols to carbonyl products is a green sustainable oxidation with no production of waste except for hydrogen, which can be an energy source. Additionally, a reusable heterogeneous catalyst is valuable from the viewpoint of process chemistry and water is a green solvent. We have accomplished the palladium on carbon (Pd/C)‐catalyzed dehydrogenation of primary alcohols to carboxylic acids in water under a mildly reduced pressure (800 hPa). The reduced pre

Hydrogen gas can be generated from simple alkanes (e.g., n-pentane, n-hexane, etc.) and diethyl ether (Et₂O) by mechanochemical energy using a planetary ball mill (SUS304, Fritsch Pulverisette 7), and the use of stainless steel balls and vessel is an important factor to generate the hydrogen. The reduction of organic compounds was also accomplished using the in-situ-generated hydrogen. While the use of pentane as the hydrogen source facilitated the reduction of the olefin moieties, th

The first total synthesis of (R,R,R)-bejarol and its (3R,5S,9R)-isomer has been accomplished which confirms the absolute configuration of the natural products. The key step is the gold-catalyzed cycloisomerization of the enantiomerically pure beta-hydroxyallenes 12/13 to the corresponding dihydropyrans 14/15.

Abstract An efficient and simple deuteration method of arenes using the platinum on carbon‐isopropyl alcohol‐cyclohexane‐deuterium oxide combination under hydrogen gas‐free conditions was accomplished. Since the hydrogen–deuterium exchange reaction cannot be promoted without isopropyl alcohol, zerovalent platinum metal (on carbon) is self‐activated by the in situ ‐generated very low amount of hydrogen or hydrogen–deuterium gas derived from isopropyl alcohol or isopropyl alcohol‐ d 1 . Deuterium‐

A one-pot continuous-flow method for hydrogen (deuterium) generation and subsequent hydrogenation (deuterogenation) was developed using a stainless-steel (SUS304)-mediated ball-milling approach. SUS304, especially zero-valent Cr and Ni as constituents of the SUS304, and mechanochemical processing played crucial roles in the development of the reactions.

Abstract Deuterium‐labeled sugars can be utilized as powerful tools for the architectural analyses of high‐sugar‐containing molecules represented by the nucleic acids and glycoproteins, and chiral building blocks for the syntheses of new drug candidates (heavy drugs) due to their potential characteristics, such as simplifying the 1 H NMR spectra and the stability of CD bonds compared with CH bonds. We have established a direct and efficient synthetic method of deuterated sugars from non‐labele

Abstract Pyridine N ‐oxide works as an effective oxidant of 1,2‐diarylalkynes at 120 °C to form benzil derivatives under Pd/C‐catalyzed solvent‐free conditions, and Pd/C could be reused up to five times after simple filtration.

Abstract We have developed a platinum on carbon‐isopropyl alcohol‐catalyzed and widely applicable defluorination method for fluoroarenes, and the addition of water and sodium carbonate efficiently accelerated the reaction. The defluorination readily occurred under the reaction conditions in comparison with the dehalogenation of other aromatic halides (fluorine>chlorine>bromine≫iodine).

Arene nuclei efficiently underwent the hydrogen (H)–deuterium (D) exchange reaction catalyzed by platinum group metals on carbon in a mixed solvent of 2-propanol and D2O at room temperature to produce deuterium-labeled arenes. Platinum on carbon (Pt/C) and iridium on carbon (Ir/C) were applicable catalysts, and the various arenes bearing a carbonyl group, fluorine, phenolic hydroxy group, amino group, or phosphonic acid on the aromatic nucleus were effectively deuterated. Nonheating conditions a

Deuterium-labeled compounds are widely utilized in various scientific fields. We summarize the recent advances in the direct deuteration of sugar, saturated fatty acid, and arene derivatives using heterogeneous platinum group metal on carbon catalysts by our research group. Hydrogen gas is a key catalyst-activator to facilitate the present H-D exchange reactions. In this review, the direct activation method of catalysts using in situ-generated hydrogen based on the dehydrogenation of alcohols is

Methyl and benzyl ethers are widely utilized as protected alcohols due to their chemical stability, such as the low reactivity of the methoxy and benzyloxy groups as leaving groups under nucleophilic conditions. We have established the direct azidation of chemically stable methyl and benzyl ethers derived from secondary and tertiary benzyl alcohols. The present azidation chemoselectively proceeds at the secondary or tertiary benzylic positions of methyl benzyl ethers or unsymmetrical dibenzyl et

The ring-opening allylation and azidation of 2,5-dihydrofurans has been accomplished with allyltrimethylsilane or Me(3)SiN(3) in the presence of catalytic amounts of HAuCl(4) x 3 H(2)O. Whereas the allylation proceeds regioselectively in the 2-position to afford 2,6-dien-1-ols, the azidation takes place in the 4-position exclusively.

A robust and quantitative gaseous hydrogen generation method has been developed in an effort to achieve efficient H2 generation derived from H2O. The present reaction could be achieved by a simple ball friction (milling) reaction of H2O using a planetary ball mill machine with a stainless-steel vessel and balls. It was mediated by metals as an element of stainless steel of the ball mill and also promoted by mechanochemical processing.