Synthesis of substituted coumarins via Brønsted acid mediated condensation of allenes with substituted phenols or anisoles.

Coumarins were obtained from the condensation of electron-rich arenes with allenes in the presence of TfOH in good yield. Depending on the substituent pattern of allenes employed, the general synthetic method of 4-substituted and 3,4-disubstituted 3-arylcoumarins has been developed. Readily available allenes were employed as the three-carbon atom sources constituting the coumarin skeleton.

Facile nucleophilic substitution of sulfonyl oxime ethers: an easy access to oxime ethers, carbonyl compounds and amines.

Sulfonyl oxime ethers undergo facile nucleophilic substitutions with various nucleophiles to yield the corresponding oxime ethers which provide an easy access to amines and carbonyl compounds.

Palladium-catalyzed cross-couplings of 1,3-butadien-2-yl species with organoindiums generated from allenylmethyl bromide and indium.

An organoindium generated from the reaction of indium with allenylmethyl bromide is an efficient nucleophile in Pd-catalyzed cross-couplings, producing 1,3-butadienes; cross-couplings followed by [4 + 2] cycloadditions gave six-membered carbocycles in a one-pot process.

Regioselective allylgallation of terminal alkynes.

The reactions of terminal alkynes with allylgallium reagents generated in situ from gallium and allyl bromides gave the corresponding 1,4-dienes in good yield via Markovnikov addition in THF at 70 degrees C.

Cyclization of 1-bromo-2,7- and 1-bromo-2,8-enynes mediated by indium.

[reaction: see text] The cyclization of 1-bromo-2,7- and 1-bromo-2,8-enynes mediated by indium in DMF produced five- and six-membered cyclic compounds. Although KI was a necessary additive in the cyclization of terminal 1-bromo-2,7-enynes to give the desired products at 25 degrees C, reactions of terminal 1-bromo-2,8-enynes and internal 1-bromo-2,7-enynes with indium proceeded at 100 degrees C in DMF without KI. After cyclizations, subsequent cross-coupling reaction and iodolysis increase the usefulness of this reaction.

Highly efficient Pd-catalyzed carbonylative cross-coupling reactions with tetraorganoindates.

Tetraorganoindates, which were prepared easily from the reaction of 1 equiv of InCl(3) with 4 equiv of organometallics, could be employed as effective nucleophilic cross-coupling partners in Pd-catalyzed carbonylative cross-coupling reactions with a variety of organic electrophiles. The present method gave unsymmetrical ketones and 1,4-diacylbenzenes in good yields with highly efficient transfer of almost all the organic groups attached to the indium under a carbon monoxide atmosphere in THF at 60 degrees C.

Highly efficient iridium-catalyzed oxidation of organosilanes to silanols.

Hydrolytic oxidation of organosilanes to the corresponding silanols can be performed highly efficiently with a catalyst system of [IrCl(C(8)H(12))](2) under essentially neutral and mild conditions, and various types of silanols are produced in good to excellent yields.