ロジウム触媒によるアルキン,アレンおよび共役エノンのアルキニル化反応

抄録

Rhodium-catalyzed alkynylation of carbon-carbon unsaturated bonds giving hydroalkynylation products took place in high yields with high stereoselectivity. Selective hydroalkynylation of internal alkynes with silylacetylenes giving 1, 3-enynes was realized by use of a hydroxorhodium catalyst. Asymmetric 1, 3-rearrangement of an alkynyl group of alkynyl alkenyl carbinols giving β-alkynylketones took place in high yields with high enantioselectivity in the presence of a hydroxorhodium/(R)-binap catalyst, which includes a key β-alkynyl elimination step in the cat-alytic cycle. Rhodium-catalyzed asymmetric conjugate alkynylation of α, β-unsaturated ketones giving β-alkynylketones was realized by use of (triisopropylsilyl) acetylene combined with (R)-DTBM-segphos as a chiral phosphine ligand, where the sterically bulky substituents on the silicon and phosphorus atoms suppress the alkyne dimerization. It was found that the presence of an acid was essential in the rhodium-catalyzed asymmetric addition of terminal alkynes to diarylphosphinylallenes giving exo-enynes in high yields with high regio- and enantioselectivity, where the stereochemical outcome is determined at the protonolysis of the π-allylrhodium(I) intermediate involved in the catalytic cycle.