Benzenes hydrogermylation

It was pointed out earlier that benzene and methylbenzenes do not add to HGeCl3 under normal conditions although some of them do participate in deuterium exchange with DGeCl3. The general hydrogermylation equation (equation 50) vividly reflects a sequence of heterolytic stages of exhaustive addition to the aromatic double bonds. 

The reaction with benzene proceeds under the most drastic conditions. At a molar ratio HGeCl3 benzene = 2.5 1, a temperature of 140 °C and a pressure of 14 kbar, the degree of conversion of benzene did not exceed 70% after 6 hours. A complex mixture of products is formed among which, after treatment of the reaction mixture with an excess of MeMgBr in ether, the products 66, 67 and 68 of the double and complete hydrogermylation which are formed in very small yields were identified by using gas chromatography-mass spectrometry combination (equation 54). 

Hydrogermylation of naphthalene, phenanthrene, anthracene and 9-Me-anthracene to form 69-71 proceed in the usual way, in accordance with equations 55-57. Reactions with anthracene and 9-methylanthracene (MA) in benzene solution at inert atmosphere lead to a single isomer of 9-trichlorogermyl-9-methyl-9,10-dihydroanthracene 71 (R = Me) in close to quantitative yield. The structure of 71 shows that protonation takes place in the 10 position of MA in accordance with the orientation effect of the Me group, as happens in the reactions of MA with classical superacids which give a stable <7-complex. ... 

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