Taichi Nakano

Synthesis of (Z)-1-aryl-2-(germyl)-1-(stannyl)ethenes and the related ethenes, precursors to stereodefined germylethenes, via Pd(dba)2–P(OCH2)3CEt-catalyzed germastannation of acetylenes in THF

(Z)-1-Aryl-2-(germyl)-1-(stannyl)ethenes are synthesized in high yields by the addition of tributyl(triethylgermyl)stannane to arylacetylenes catalyzed by a specific combination catalyst, Pd(dba)2 and 4-ethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, in tetrahydrofuran. Ethynylthiophene and 2-methyl-3-butyn-2-ol are also subject to the germastannation to afford the respective adducts in high yields. In addition, the JSn–H and 13C-NMR data for their adducts are presented.

Palladium complex-catalyzed germylation of allylic halides using (germyl)stannanes

Abstract (Triethylgermyl)tributylstannane reacts metal-selectively with allylic halides at room temperature (r.t.) in the presence of tris(dibenzylideneacetone)dipalladium, Pd 2 (dba) 3 CHCl 3 , to provide an alternative route to allylgermanes. (Dimethylphenylgermyl)tributylstannane regio- and stereoselectively reacts more readily with allylic halides than (triethylgermyl)tributylstannane affording the corresponding allylgermanes in quantitative yields.

Palladium-Catalyzed Reactions of Hexaethyldigermane with 2-Alkenyl Halides

The reaction of hexaethyldigermane with allylic halides proceeded regioselectively in the presence of a catalytic amount of Pd2(dba)3 at temperatures of 120°C ∼ 170°C and gave allylgermanes in 42 ∼ 95% yields. The results indicate that the present reaction proceeds predominately through an SN2-type mechanism over an SN2′-type one.

An alternative route to allylgermanes by the palladium-catalyzed reaction of germylsilanes with allylic halides

Abstract Pd(dba)2 (bis(dibenzylideneacetone)palladium complex) effectively catalyzes the reaction of (dimethylphenylgermyl)trimethylsilane with 2-alkenyl halides to bring about metal-, regio- and stereoselective metathesis resulting in the formation of 2-alkenylphenylgermanes with good yields. On the other hand, the reaction of (chlorodimethylgermyl)trimethylsilane with 2-alkenyl halides is effected by a palladiumue5f8phosphine complex to give 2-alkenylchlorogermanes selectively. Germylation of 3,4-dichloro-1-butene with (dimethylphenylgermyl)trimethylsilane forms 1,4-bis(dimethylphenylgermyl)-2-butene with a high yield.

Palladium-catalyzed metathesis of phenylalkyl- or chloroalkyldigermanes with allylic chlorides at room temperature

Abstract Metathesis of phenylalkyldigermanes (1,2-diphenyltetraethyl-, 1,2-diphenyltetramethyl-, phenylpentaethyl- or phenylpentamethyldigermane) or chloroalkyldigermanes (1,2-dichlorotetraethyl- or 1,2-dichlorotetramethyldigermane) with allylic chlorides proceeds smoothly even at room temperature in the presence of tris(dibenzylideneacetone)dipalladium(0) to afford the corresponding 2-alkenylgermanes in good to high yields.

The Reaction of Allyltributylgermane with Organic Halides

The reaction of allyltributylgermane with organic halides in the presence of azobisisobutyronitrile or dichlorotris (triphenylphosphine) ruthenium (II) brought about allylation of organic halides to give the corresponding products in moderate yields. The reaction using AIBN as an initiator may be concluded to proceed through a SH, mechanism.