Lodomethylzinc iodide

Certain organometallic compounds resemble caibenes in their reactions and aie refened to as carbenoids. lodomethylzinc iodide (Section 14.12) is an exfflnple. 

Alkene lodomethylzinc iodide Cyclopropane Zinc derivative iodide... 

Chiral Ligand for Asymmetric Catalysis. Dimethyl l-tartrate is a demonstrated chiral ligand for the Ti -catalyzed asymmetric epoxidation of allylic alcohols (Sharpless epoxidation), and the Zn -mediated asymmetric cyclo-propanation of allylic alcohols (Simmons-Smith reaction), see lodomethylzinc Iodide Enantioselectivities in these reactions... 

Gloss and Moss have suggested the term carhenoid to describe intermediates that exhibit reactions quahtatively similar to those of carbenes without necessarily being free divalent carbon species. When carbenes are coordinated with metals they are known as carbenoids that have modified reactivities. lodomethylzinc iodide is often referred to as a carhenoid, because it resembles a carbene in its chemical reactions (Simmons-Smith reaction) (Scheme 5.14). Rhodium and copper carbenoids are unstable whereas some transition metals such as tungsten and chromium form stable and isolable carbenoids called metallocarhenes or Fischer carbenes. Carbenoids are structurally related to singlet carbenes and possess similar reactivity. 

Similarities Between the Mechanisms of Reaction of an Alkene with lodomethylzinc Iodide and a Peroxy Acid 624... 

Methylene ( CH2), the simplest carbene, can be prepared by decomposition of the highly toxic and explosive reagent diazomethane (CH Nj). However, more easily used reagents have been developed that, while they do not produce methylene directly, function as methylene transfer agents. They are called carbenoid species because they react like carbenes. lodomethylzinc iodide, known as the Simmons-Smith reagent, is a carbenoid. In the Simmons-Smith method, diiodomethane reacts with a zinc-copper alloy to produce an intermediate I—CH Zn—I compound. 

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