Diiodomethane, carbenoid generation from

Reactions of halogen-stabilized carbenoids with imines have been carried out using preformed lithium species e.g. equation or via a carbenoid generated from diiodomethane utilizing zinc-copper... 

Reactions of halogen-stabilized carbenoids with imines have been carried out using prefoimed lithium species (e.g. equation 36), or via a carbenoid generated from diiodomethane utilizing zinc-copper couple (Simmons-Smith conditions). A stereospecific ring closure is observed after the addition of lithiodichloromethane to a benzaldimine (equation 37).The addition of lithiochloro(phenylsulfon-yl)methane to aromatic imines affords 2-phenylsulfonyl-substituted aziridines, which can be deproton-ated and alkylated in excellent yield (Scheme 20). 

The carbenoid generated from diiodomethane/diethylzinc is often found to be more reactive than the conventional Simmons-Smith reagent. Thus, in the case of 1-alkenylboronic acid esters, where diazomethane failed to cyclopropanate trisubstituted derivatives (Section 1.2.1.1.1.) diiodomethane/diethylzinc gave good yields of the required products 16. ... 

A cyclopropanation of an alkene using the carbenoid reagent generated from diiodomethane and the zinc-copper couple, (p. 358)... 

Another reaction that builds a cyclopropane ring onto a carbon-carbon double bond is called the Simmons-Smith reaction. This reaction does not actually involve a car-bene, but rather a carbenoid, an organometallic species that reacts like a carbene. This species is generated by reaction of diiodomethane with zinc metal from a special alloy of zinc and copper ... 

Simmons—Smith Cyclopropanation. Simmons-Smith cyclopropana-tions have been known for many years as an efficient method for cyclopropanation via methylene transfer to olefinic substrates. Although a stoichiometric amount of reagent is mostly required, the superior reactivity and selectivity make the method inseparable from cyclopropanation. The classical Simmons-Smith cyclopropanation involves a zinc carbenoid reagent (IZnCH2l) generated by the oxidative addition of metallic zinc to diiodomethane by a copper metal as an activator (48). This somewhat cumbersome procedure was later replaced by other more easily accessible and reproducible methods. The benchmark replaces the... 

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