A new route to substituted phenols has been developed by cationic rhodium(I)/BINAP complex-catalyzed decarboxylative [2 + 2 + 2] cycloadditions of 1,6- and 1,7-diynes with commercially available vinylene carbonate.
A cationic rhodium(I)/rac-BINAP complex catalyzes chemo- and regioselective formal cross-cyclotrimerizations of alkynes with enol ethers or acetates. Commercially available and cheap liquid enol ethers and acetates could be used as convenient gaseous alkyne equivalents in the present rhodium catalyses.
A deep desulfurization process for light oil has been investigated, on the basis of photosensitized oxidation using a triplet photosensitizer and hydrogen peroxide in an oil/water two-phase liquidliquid extraction system. Dibenzothiophene (DBT) in tetradecane was effectively desulfurized. This was achieved via the indirect photoexcitation of DBT, using benzophenone (BZP) under photoirradiation conditions of wavelength λ > 280 nm, and the effective oxidation of the excited DBT by H 2 O 2 , suppressing the photodecomposition of H 2 O 2 . The desulfurization of commercial light oil was also achieved in this process by the addition of both BZP and H 2 O 2 , and the sulfur content was reduced from 0.2 to 0.05 wt % by 48 h of photoirradiation, to meet with the new regulation in Japan. Although C5 and C6 alkyl-substituted DBTs were found to be the most difficult components to be desulfurized, they too were desulfurized effectively in the presence of BZP and H 2 O 2 . The photodecomposed sulfur-containing compounds removed into the water phase were separated successfully, using column adsorption with aluminum oxide as the adsorbent. The H 2 O 2 solution recovered is also reusable for the desulfurization process.
A cationic rhodium(I)/bisphosphine complex catalyzes carboxylative cyclizations of 1,6-diynes, leading to cyclic dienyl carboxylates, in high yields with high chemo-, regio-, and stereoselectivities under mild reaction conditions.
A convenient synthesis of perfluoroalkylated benzenes and pyridines has been achieved by a cationic Rh(I)/modified BINAP-complex-catalyzed chemo- and regioselective [2 + 2 + 2] cycloaddition of alkynes with a perfluoroalkylacetylene and a perfluoroalkylnitrile.
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