Ytterbium(II) Iodide


[19357-86-9]  · I2Yb  · Ytterbium(II) Iodide  · (MW 426.84)

(promotes the reduction of conjugated alkenes, leaving isolated alkenes unaffected;1a,2 effects the reductive cyclization of halo ketones with good diastereoselectivities3)

Physical Data: light yellow powder; mp 780 °C; bp 1300 °C; structure determined by X-ray diffraction.

Solubility: sol dilute acid, H2O.

Preparative Methods: typically prepared in situ via oxidation of Ytterbium(0) metal with various organic dihalides such as 1,1-Diiodoethane or Diiodomethane;1a may also be prepared from reaction of ytterbium metal with excess HgI2 or from the reaction of excess ytterbium metal with NH4I and NH3.1b -d

Handling, Storage, and Precautions: should be kept in an inert atmosphere; subject to hydrate formation.1

Reduction of Conjugated Alkenes.

Ytterbium diiodide effects the reduction of conjugated alkenes while isolated double bonds remain unchanged under the same reaction conditions.1a Cinnamic acid and ethyl cinnamate are cleanly reduced to the saturated carboxylic acid or ester when subjected to YbI2 in THF/MeOH (eqs 1 and 2).2 The analogous conjugated ketone and aldehyde, however, suffer competition between C=C and C=O reduction. Isolated ketones appear to be inert under similar reaction conditions.

Reductive Cyclization of Halo Ketones.

Ytterbium(II) iodide has been utilized in the synthesis of five-, six-, and seven-membered rings in good yield from 2-(o-iodoalkyl)cycloalkanones (eqs 3 and 4).3 In these examples, the ytterbium(II) iodide complex was found to give somewhat higher diastereoselectivities than Samarium(II) Iodide.

1. (a) Namy, J. L.; Girard, P.; Kagan, H. B. NJC 1977, 1, 5. (b) Kim, B. Y.; Kwapisz, R.; Eick, H. A. J. Solid State Chem. 1989, 80, 163. (c) Lasocha, W.; Voos-Esquivel, C. A.; Hodorowicz, S. A.; Kim, B. Y.; Eick, H. A. J. Solid State Chem. 1988, 74, 67. (d) Tilley, T. D.; Boncella, J. M.; Berg, D. J.; Burns, C. J.; Andersen, R. A. Inorg. Synth. 1990, 27, 146.
2. Girard, P.; Namy, J. L.; Kagan, H. B. JACS 1980, 102, 2693.
3. Molander, G. A.; Etter, J. B. JOC 1986, 51, 1778.

Gary A. Molander & Christina R. Harris

University of Colorado, Boulder, CO, USA

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