Development of Asymmetric Allylation Reaction Using Allygermanes

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We focused on organogermanium compounds, which have attracted little attention of synthetic organic chemists, in this project and studied on the allylation reactions of carbonyl compounds by means of allylgermanes.On treatment of aldehyde and tetraallylgermane in the presence of catalytic amount of scandium (III) triflate in aqueous acetonitrile, allylation of aldehyde proceeded smoothly to afford homoallylic alcohols in excellent yields.For the allylation of aldimines, allyitriethylgermane was found to be quite effective and scandium (III) triflate catalyzed allylation of aldimines in acetonitrile furnished homoallylic amines in high yields. Present allylation reaction showed high chemoselectivity toward aldimines in preference to aldehyde. Thus, three component synthesis of homoallylic amines from aidehyde, amine, and allylgermane proceeded smoothly to afford homoallylic amines in good yields.It was found that activation of aldimines was achieved by the combination of BFィイD23ィエD2・OetィイD22ィエD2 and CHィイD23ィエD2 COィイD22ィエD2 H, which are cheaper and easier to handle than scandium (III) triflate.Next, enantioselective allylation of aldehyde with allylgermane was studied. Allylation of aldehyde took place highly enantioselectively by means of a chiral catalyst, derived from R-(+)-binaphthol and titanium tetraisopropoxide, to afford homoallylic alcohols as high as 89% ee. This is the first enantioselective reactions by use of allylgermanes as allylic organometallics.