The condensation of diethylgermanium dihydride (I) with methyl acrylate (II) gives diethyldi-(beta-carbomethoxyethyl)germane (III), which is cyclized by treatment with potassium tert-butoxide in refluxing toluene yielding carbomethoxy-4,4-diethyl-4-germacyclohexanone (IV). The decarboxylative hydrolysis of (IV) with refluxing 20% aqueous H2SO4 affords 4,4-diethyl-4-germacyclohexanone (V), which is condensed with ethyl cyanoacetate (VI) by means of ammonium acetate acetic acid in refluxing benzene giving ethyl alpha-cyano-alpha-(4,4-diethyl-4-germacyclohexylidene)acetate (VII). The treatment of (VII) with KCN in ethanol-water, and then with refluxing aqueous HCl yields 4,4-diethyl-4-germacyclohexane-1-carboxy-1-acetic acid (VIII), which is then converted into its cyclic anhydride (IX) by reaction with refluxing acetic anhydride. The reaction of (IX) with 3-dimethylaminopropylamine (X) at 180 C gives N-(3-dimethylaminopropyl)-2-aza-8,8-diethyl-8-germaspiro[4.5]decane-1,3-dione (XI), which is finally reduced with LiAlH4 in benzene-ether.

The condensation of diethylgermanium dihydride (I) with methyl acrylate (II) gives diethyldi-(beta-carbomethoxyethyl)germane (III), which is cyclized by treatment with potassium tert-butoxide in refluxing toluene yielding carbomethoxy-4,4-diethyl-4-germacyclohexanone (IV). The decarboxylative hydrolysis of (IV) with refluxing 20% aqueous H2SO4 affords 4,4-diethyl-4-germacyclohexanone (V), which is condensed with ethyl cyanoacetate (VI) by means of ammonium acetate acetic acid in refluxing benzene giving ethyl alpha-cyano-alpha-(4,4-diethyl-4-germacyclohexylidene)acetate (VII). The treatment of (VII) with KCN in ethanol-water, and then with refluxing aqueous HCl yields 4,4-diethyl-4-germacyclohexane-1-carboxy-1-acetic acid (VIII), which is then converted into its cyclic anhydride (IX) by reaction with refluxing acetic anhydride. The reaction of (IX) with 3-dimethylaminopropylamine (X) at 180 C gives N-(3-dimethylaminopropyl)-2-aza-8,8-diethyl-8-germaspiro[4.5]decane-1,3-dione (XI), which is finally reduced with LiAlH4 in benzene-ether.

The condensation of diethylgermanium dihydride (I) with methyl acrylate (II) gives diethyldi-(beta-carbomethoxyethyl)germane (III), which is cyclized by treatment with potassium tert-butoxide in refluxing toluene yielding carbomethoxy-4,4-diethyl-4-germacyclohexanone (IV). The decarboxylative hydrolysis of (IV) with refluxing 20% aqueous H2SO4 affords 4,4-diethyl-4-germacyclohexanone (V), which is condensed with ethyl cyanoacetate (VI) by means of ammonium acetate acetic acid in refluxing benzene giving ethyl alpha-cyano-alpha-(4,4-diethyl-4-germacyclohexylidene)acetate (VII). The treatment of (VII) with KCN in ethanol-water, and then with refluxing aqueous HCl yields 4,4-diethyl-4-germacyclohexane-1-carboxy-1-acetic acid (VIII), which is then converted into its cyclic anhydride (IX) by reaction with refluxing acetic anhydride. The reaction of (IX) with 3-dimethylaminopropylamine (X) at 180 C gives N-(3-dimethylaminopropyl)-2-aza-8,8-diethyl-8-germaspiro[4.5]decane-1,3-dione (XI), which is finally reduced with LiAlH4 in benzene-ether.