We designed and synthesized a novel Si-rhodamine derivative, NORD-1, as a red-light-controllable nitric oxide (NO) releaser, on the basis of photoredox parameter analysis. Red-lightresponsive NO release from NORD-1 was confirmed by ESR spin trapping and quantified with an NO electrode and by means of Griess assay. The NO release cross section (ε 656 nm •Φ NO ) of NORD-1 was calculated to be 3.65 × 10 2 , which is larger than that of a previously reported yellowish-green-light-controllable NO releaser, NO-Rosa5. The photoresponsiveness of NO release from NORD-1 was precise and efficient enough to induce vasodilation ex vivo under Magnus test conditions. Finally, we showed that intracavernous pressure (ICP) could be controlled in rats in vivo with the combination of NORD-1 and a red-light source without increasing systemic blood pressure, which is a serious side effect of usual NO releasers, such as nitroglycerin and isopentyl nitrite. NORD-1 is expected to be a useful chemical tool for NO research, as well as a candidate agent to control the circulatory system.

No abstract

Nitroaromatics are usually prepared using a mixed acid of nitric acid with strong acids. However, the use of strong acids caused dangerous work-up and the disposal of large amounts of acid-waste. Therefore, much effort has been made on the improvement of nitration process without strong acids. We examined solid-phase aromatic nitration with Mg(NO 3 ) 2 on silica gel in order to establish the nitration process without strong acids. The nitration of 1,2-and 1,3-, 1,4-dimethoxybenzenes and 4-methylanisole with Mg(NO 3 ) 2 proceeded by heating on silica gel at 150˚C for 4 -5 h to produce the nitroaromatics. The nitration of 1,3,5-trimethoxybenzene produced the nitrated dimer, 2,4,6,2', 4',6'-hexamethoxy-3-nitrobiphenyl, which was not isolated in other solid-phase nitration. In the cases of naphthalene derivatives, the α-nitrated compounds were obtained. In the cases of p-cresol and 2-naphthol, the esterification occurred at the hydroxyl group to give 4-tolyl nitrate and 2-naphthyl nitrate, respectively. It is synthetic interest to note that nitrate esters were isolated in solid phase. Thus Mg(NO 3 ) 2 -SiO 2 composite was mild reagent for solid-phase nitration. Acidity of Mg(NO 3 ) 2 -SiO 2 composite was determined to be pH 0.96 by the measurement of absorption spectra on a micro spectrophotometer using meso-tetra(p-cyanophenyl)porphyrin as a pH-indicator. Mg(NO 3 ) 2 -SiO 2 composite made acidic conditions. Therefore, it was suggested that Mg(NO 3 ) 2 reacted with proton on silica gel to form the 2 NO + . Thus, electron-rich aromatic hydrocarbons led the efficient nitration through electrophilic attack of 2 NO + . After the nitration, acidic Mg(NO 3 ) 2 -SiO 2 composite could be turned into neutrality by exposing wet conditions and disposed safely since the composite did not involve harmful elements. Thus the solid-phase nitration using Mg(NO 3 ) 2 -SiO 2 composite will provide safety and environmentally conscious chemical process.

No abstract

No abstract