Samarium(II) Iodide-1,3-Dioxolane

(SmI2)

[32248-43-4]  · I2Sm  · Samarium(II) Iodide-1,3-Dioxolane  · (MW 404.16) (1,3-dioxolane)

[646-06-0]  · C3H6O2  · Samarium(II) Iodide-1,3-Dioxolane  · (MW 74.09)

(used as a formyl anion equivalent in carbonyl addition reactions of aldehyde and ketone substrates)

Solubility: sol 0.1 M in dioxolane.

Preparative Methods: SmI2 prepared in dioxolane with addition of Acetonitrile to aid in dissolving SmI2.

Handling, Storage, and Precautions: SmI2 is air sensitive and should be handled accordingly.

General Discussion.

Samarium(II) Iodide in conjunction with 1,3-dioxolane and an aryl halide has been utilized in the masked formylation of aldehydes and ketones (eqs 1 and 2).1 Aryl halides do not undergo Barbier-type coupling reactions with ketones in the presence of samarium diiodide; instead, the generated aryl radical abstracts a hydrogen atom from 1,3-dioxolane, which is used as the solvent in these types of reactions. The resulting dioxolanyl radical may then couple with the aldehyde or ketone substrate, yielding the carbonyl addition product.

Little selectivity is achieved with chiral substrates as the reaction of 4-t-butylcyclohexanone yielded a 1:1 mixture of diastereomers (eq 3).

Typical yields for the reaction are in the range of 73-77%. This reagent provides a useful method for introduction of a one-carbon unit in the aldehyde oxidation state and is in general quite mild. The reaction is limited, however, in that 1,3-dioxolane must be utilized as solvent. Consequently, more highly functionalized dioxolane substrates which are less readily available may not be suitable partners in similar reactions.


1. Matsukawa, M.; Inanaga, J.; Yamaguchi, M. TL 1987, 28, 5877.

Gary A. Molander & Christina R. Harris

University of Colorado, Boulder, CO, USA



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