We have established the first catalytic C-C and C-N bond formation reactions of O-heterocycles (e.g., tetrahydrofuran, phthalane, and lactone derivatives) using iron trichloride as a catalyst in the presence of TMSN3 or allylsilanes accompanied by the ring opening of O-heterocycles. The reactions smoothly proceeded at room temperature to give the corresponding primary saturated alcohols from the 2-substituted tetrahydrofurans, ortho-substituted benzyl alcohols from phthalanes, and saturated carboxylic acids from lactones in high yields.
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-labeled compounds with high deuterium contents can be easily isolated by the filtration of platinum on carbon and simple extraction. The present hydrogen gas-free method is safe from the viewpoint of process chemistry and various arenes possessing a variety of reducible functionalities within the molecule could be effectively and directly deuterium-labeled without undesired reduction.
Disiloxanes possessing a silicon-oxygen linkage are important as frameworks for functional materials and coupling partners for Hiyama-type cross coupling. We found that disiloxanes were effectively constructed of hydrosilanes catalyzed by gold on carbon in water as the solvent and oxidant in association with the emission of hydrogen gas at room temperature. The present oxidation could proceed via various reaction pathways, such as the hydration of hydrosilane into silanol, dehydrogenative coupling of hydrosilane into disilane, and the subsequent corresponding reactions to disiloxane. Additionally, the platinum on carbon catalyzed hydrogen-deuterium exchange reaction of arylhydrosilanes as substrates in heavy water proceeded on the aromatic nuclei at 80 °C with high deuterium efficiency and high regioselectivity at the only meta and para positions of the aromatic-silicon bond to give the deuterium-labeled disiloxanes.
Since 1,4-epoxy-1,4-dihydronaphthalenes are smoothly converted to 1-naphthol derivatives via unstable cation intermediates formed by the acid-catalyzed ring-opening reaction of the 1,4-epoxy moiety of 1,4-epoxy-1,4-dihydronaphthalenes, their nucleophilic functionalization using the cation intermediates as an active species is extremely difficult. We have accomplished the Lewis acid-catalyzed carboncarbon and carbon-nitrogen bond formations associated with the ring-opening of 1,4-epoxy-1,4-dihydronaphthalenes using nucleophiles such as allyltrimethylsilanes, trimethylsilyl cyanide and trimetylsilyl azide, by using the stabilization effect of the cation intermediate based on the introduction of appropriate substituents into the bridgehead positions of 1,4epoxy-1,4-dihydronaphthalenes to give the corresponding unique and multifunctionalized naphthalene derivatives. The present reactions could provide excellent regioselective functionalization methods using unsymmetrical substrates, which are quite difficult to achieve using transition metal-induced procedures. 521 Lewis Acid-Catalyzed Ring-Opening Functionalizations of 1,4-Epoxy-1,4-dihydronaphthalenes Scheme 5. Ring-opening functionalizations using nitrogenbridged substrate (11).Scheme 4. Proposed reaction mechanism.
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