[80-73-9]  · C5H10N2O  · 1,3-Dimethyl-2-imidazolidinone  · (MW 114.17)

(dipolar aprotic solvent1 with characteristics between THF and HMPA; solvent of choice for many types of organic reactions, especially organometallic reactions2)

Alternate Name: DMI.

Physical Data: bp 221-223 °C; d 1.044 g cm-3.

Solubility: sol water, DMF, and THF.

Form Supplied in: clear, colorless liquid; commercially available.

Analysis of Reagent Purity: bp, NMR.

Purification: distillation over calcium hydride under reduced pressure.

Handling, Storage, and Precautions: for best results, this solvent should be stored under an inert atmosphere over 4Å molecular sieves. Handle in a fume hood.

Synthesis of Homoallylic Alcohols.

DMI is the solvent of choice for palladium-catalyzed carbonyl allylation of allylic alcohols (eq 1).3 Allylation of ketones requires higher temperatures (eq 2). Preferential reaction of an aldehyde in the presence of a ketone can be achieved (eq 3). Allylic iodides can also be reacted with aldehydes and ketones in the presence of Tin(II) Fluoride4 to form homoallylic alcohols in good yield without the use of Lewis acids as additives (eq 4).

Synthesis of a-Methylene-g-butyrolactones.

Palladium-catalyzed allylation of aldehydes and ketones with ethyl a-(hydroxymethyl)acrylate in the presence of Tin(II) Chloride in DMI/water provides a-methylene-g-butyrolactones (eq 5).5 Syn selectivity has been achieved when the reactions are run using a substituted hydroxymethylacrylate.

Preparation of Trimethylsilylsodium, Trimethylsilylpotassium, and Trimethylsilyllithium.

DMI is the solvent of choice for the preparation of TMSNa, Trimethylsilylpotassium, and Trimethylsilyllithium (eq 6).6 Other polar aprotic solvents such as DMF, DMSO, and tetramethylurea (TMU) are not suitable due to their reactivity toward strong base and alkali metals. Reactions of these species are also run in DMI (eqs 7 and 8).2

Dehydrations and Dehydrohalogenation Reactions.

DMI can be used as an alternative for HMPA7 in dehydration and dehydrohalogenation reactions using Methyltriphenoxyphosphonium Iodide (MTPI) (eq 9).

Ullmann Ether Synthesis.

Preparation of m-phenoxybenzyl alcohol by condensation of m-hydroxybenzyl alcohol with chlorobenzene works best in DMI (eq 10).8 Lower yields result when the reaction is run using DMSO or DMF.

Synthesis of a-Hydroxyallenes.

Reactions of propargyl iodides with aldehydes in the presence of SnCl2 in DMI/DMF yield a mixture of a-hydroxylallenes and b-hydroxyalkynes9 (eq 11).

Wittig-Horner Reactions.

High syn selectivity is achieved in Wittig-Horner reactions between aldehydes and diphenylphosphonates when run in THF/DMI at low temperature.10 Subsequent stereospecific elimination yields cis-alkenes (eq 12).

1. Barker, B. J.; Rosenfarb, J.; Caruso, J. A. AG(E) 1979, 18, 503.
2. Sakurai, H.; Kondo, F. JOM 1976, 117, 149.
3. Masuyama, Y.; Takahara, J. P.; Kurusu, Y. JACS 1988, 110, 4473.
4. Mukaiyama, T.; Harada, T.; Shoda, S. CL 1980, 1507.
5. Masuyama, Y.; Nimura, Y.; Kurusu, Y. TL 1991, 32, 225.
6. Sakurai, H.; Kondo, F. JOM 1975, 92, C46.
7. Spangler, C. W.; Kjell, D. P.; Wellander, L. L.; Kinsella, M. A. JCS(P1) 1981, 2287.
8. Oi, R.; Shimakawa, C.; Takenaka, S. CL 1988, 899.
9. Mukaiyama, T.; Harada, T. CL 1981, 621.
10. Buss, A. D.; Warren, J. TL 1983, 24, 3931.

Ellen M. Leahy

Affymax Research Institute, Palo Alto, CA, USA

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.