Simmons-Smith Reaction - ChemTube3D

Simmons-Smith cyclopropanation, which employs carbenes derived from diethylzinc and diiodomethane, is a popular alternative to rhodium-catalyzed cyclopropanation. In the presence of a chiral diamine, Simmons-Smith cyclopropanation is enantioselective; however, selectivities are not as high as the corresponding rhodium-catalyzed reactions.

The asymmetric Simmons-Smith reaction is a cyclopropanation ..

Read "Catalytic Asymmetric Simmons—Smith Cyclopropanation of Silyl Enol Ethers

Stereoselective Simmons—Smith Cyclopropanation of …

The zinc is coupled with another metal; in the original Simmons-Smith reaction, a Zn/Cu couple was used. In the total synthesis of maoecrystal V, a Zn/Ag couple was used in diethyl ether for a higher yield and faster reaction rates.2

Regioselective Simmons–Smith-type cyclopropanations …

A detailed account on Simmons-Smith cyclopropanations of allenamides en route to amido-spiro[2.2]pentanes is described here. While the diastereoselectivity was low when using unsubstituted allenamides, the reaction is overall efficient and general, representing the most direct synthesis of both chemically and biologically interesting amido-spiro[2.2]pentane systems. With α-substituted allenamides, while the diastereoselectivity could be improved significantly based on a series of conformational analysis, both mono- and bis-cyclopropanation products were observed. Consequently, several structurally intriguing amido-methylene cyclopropanes could also be prepared.

The non-halogenated cyclopropane can be obtained by using the Simmons-Smith reaction.
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29/10/2007 · REVIEW

In the Simmons-Smith reaction, an alkene reacts with an organozinc carbenoid to form a cyclopropane.1 To form the organozinc carbenoid, a zinc-copper couple (Zn/Cu) reacts with a dihalomethane, often diiodomethane (CH2I2). This reaction produces iodomethylzinc iodide, an organozinc carbenoid with the structure I-Zn-CH2-I. Conventionally, excess of the dihalomethane is added to a solution containing the alkene and excess Zn via syringe to form the carbenoid. Then, a concerted reaction occurs between the organozinc carbenoid and the alkene; the electrons from the double bond form a bond with the carbon atom in the organozinc compound, the electrons in the carbon-zinc bond form a bond with the alkene, and electrons from iodine will form a bond with zinc. This reaction is stereospecific, preserving the positions of the groups on the alkene with respect to each other.

A Gene-Expression Signature as a Predictor of Survival …

van de Vijver, M.D., Ph.D., Yudong D