Hydrogermylation, alkynes

Tri(2-furyl)germane63,127 130 has been shown to be a useful hydrogermylation reagent for alkenes,127,128 dienes,129 alkynes,129,130 and carbonyl species (Equations (97) and (98), Table 17).127 It has been employed to selectively hydrogermylate the double bond of a,/3-unsaturated carbonyl compounds (Equation (99)).127 This species can also be used to affect the hydrogermylcarbonylation of alkynes in the presence of CO (Equation (100)).130... 

Alkynes react with the bulky germanium hydride (MejSdjGeH to selectively yield (Z)-alkenes (Equation (105)).67 The hydrogermylation of alkynols or alkynes can be catalyzed by a rhodium complex (Equation (106), Table 18) and some of the intermediates were identified (Scheme 16).132 Similar rhodium species react with alkynes to yield alkenyl complexes,133 and other transition metal complexes have been employed as hydrogermylation catalysts including those containing palladium.134,135... 

A range of addition reactions of (TMS)3GeH with alkynes, alkenes, ketones, azines, and quinones has been studied using EPR. In addition, synthetic studies of hydrogermylation of alkynes have shown that the reaction proceeds regio- and stereo-selectively, whereas reactions with alkenes do not take place (presumably owing to the reversibility of the germyl radical addition) (Scheme 29). 

In a manner similar to silylformylation, germylformylation of 1-alkynes catalyzed by 12 proceeds with Bu aGeH under CO pressure (20 atm). However, it is difficult to completely suppress hydrogermylation of 1-alkynes as the side-reaction. ... 

Hydrogermylation chemistry has been employed to make germanium-carbon bonds at surfaces via the reaction of alkynes and alkenes with the Ge-H bonds of HF-treated surfaces. Recently, this method has also been employed to functionalize the surface of germanium quantum dots (Figure 2). 

Terminal alkynes can be conveniently silanized as shown in reaction 6 They undergo platinum-catalysed hyrosilylation and hydrogermylation. The germylation reaction 7 is almost selective for the terminal carbon... 

Additions of trihalogermanes to alkynes, alkenes and carbonyl compounds have been reviewed. Hydrogermylation of phenylacetylene with triphenylgermane in the presence of Pd(PPh3)4 gives a mixture of three vinylgermanes (equation 42). ... 

RXN17 Hydroboration, Hydrogermylation, Hydrosilylation and Hydrostannation of Alkynes, Allenes, Dienes and Enynes... 

Other frans-hydrometalation of alkynes includes the use of a combination of InCls and DIBAL to produce alkenyl indium species [43], and a Lewis acid catalyzed hydrogermylation of terminal/intemal alkynes (Fig. 19) [44]. In both cases, frans-hydrometalation was believed to account for the stereoselectivity of the reactions. 

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