Synthesis of some functional germanium heterocycles: Germirenes and derivatives of germacyclopentene

Abstract

The germirene, 1,1,4,4-tetraiodo-2,3,5,6-tetramethyl-1,4-digerma-2,5-cyclohexadiene, (VI), was prepared from germanium diiodide and 2-butyne. Reduction with lithium aluminum hydride replaces the iodine with hydrogen. The hydride reacts with mercuric chloride to form trans-1,4-dichloro-2,3,5,6-tetramethyl-1,4-digerma-2,5-cyclohexadiene, (VIII), which in turn reacts with carbon tetrachloride to produce 1,1,4,4-tetrachloro-2,3,5,6-tetramethyl-1,4-digerma-2,5-cyclohexadiene, (X). Compound (VIII) reacts with methyl Grignard reagent to give 1,2,3,4,5,6-hexamethyl-1,4-digerma-2,5-cyclohexadiene, (IX). Attempts to form metal carbonyl complexes of (VIII) and (IX) are described.Bromine adds to the double bond of 1,1-dibromo-1-germa-3-cyclopentene to give 1,1,3,4-tetrabromo-1-germacyclopentane which could not be dehydrohalogenated to a functional germacyclopentadiene. 1,1-dimethyl-2-bromo-1-germa-3-cyclopentene was also prepared, but could not be dehydrohalogenated.