GERMYLENES AND GERMANIUM DOUBLY BONDED SPECIES IN HETEROCYCLIC ORGANOGERMANIUM CHEMISTRY. SOME RESULTS FROM THE TOULOUSE GROUP

Abstract

Germylenes, divalent germanium species, and germanium derivatives with Ge = Y double bonds (Y = C=, O, S, N–, P–) are powerful synthetic reagents in organometallic chemistry. The germylenes exhibit properties analogous to those of carbenes and have been shown to insert into various σ-bonds such as carbon-heteroelement, metal-carbon, and metal-heteroelement of heterocyclic derivatives with ring expansion. The addition of germylenes to various unsaturated compounds (dienes, orthoquinones, carbonyl compounds, imines, nitrosobenzene) leads, as a rule, to cycloadducts with low stability except for dienes and quinones. The doubly bonded germanium species are highly reactive and widely used in organometallic synthesis in various types of reactions such as:

– addition (or insertion reactions) to various σ-bonds of organometallic compounds;

– insertion reactions with ring expansion of small organic rings;

– cycloaddition reactions with 1–2, 1–3, and 1–4 dipolar reagents.

The mechanism and stereochemistry of some reactions are discussed.

Also published in Chemistry of Heterocyclic Compounds, 1999, 35 (9), pp 1013-1032

http://link.springer.com/article/10.1007/BF02251793