[33598-72-0]  · C3H7IZn  · Ethyliodomethylzinc  · (MW 235.39)

(cyclopropanation reagent1)

Alternate Name: Sawada reagent.

Preparative Methods: obtained by the reaction of Ethylzinc Iodide with Diiodomethane in ether at 30-35 °C1 or by the reaction of diiodomethane with Diethylzinc.2

Handling, Storage, and Precautions: decomposes slowly at room temperature; should be handled under nitrogen and in the absence of moisture.

Cyclopropanation Reactions.

Ethyliodomethylzinc (Sawada reagent) is a useful cyclopropanation reagent which gives, in many cases, better yields than the Simmons-Smith reagent2,3 (see Ethylzinc Iodide and eqs 1 and 2).1 Although formulated as ethyliodomethylzinc, the actual reagent may well be Iodomethylzinc Iodide.1 The difference of reactivity with the Simmons-Smith reagent may be due to the presence of different zinc salts and to the slightly different reaction conditions used for their generation. Contrary to the Furukawa reagent (CH2I2 and Et2Zn, see Diethylzinc), the Sawada reagent (CH2I2 and EtZnI) does not react well with enol ethers1 and gives moderate yields in the case of a,b-unsaturated esters (eq 3).1

Interestingly, the polycyclic ketone (1) is efficiently converted to the corresponding cyclopropane derivative (2) in high yield (eq 4).4 The related aluminum reagent prepared by the reaction of Trimethylaluminum and CH2I2 has proven to be a powerful cyclopropanation reagent (eqs 5 and 6).5 Finally, ethyl iodomethylzinc allows the methylation of various phenols at high temperature (eq 7).6

1. Sawada, S.; Inouye, Y. BCJ 1969, 42, 2669.
2. (a) Simmons, H. E.; Cairns, T. L.; Vladuchick, S. A.; Hoiness, C. M. OR 1973, 20, 1. (b) Furukawa, J.; Kawabata, N. Adv. Organomet. Chem. 1974, 12, 83.
3. Detty, M. R.; Paquette, L. A. JACS 1977, 99, 821.
4. Fitjer, L.; Kühn, W.; Klages, U.; Egert, E.; Clegg, W.; Schormann, N.; Sheldrick, G. M. CB 1984, 117, 3075.
5. Maruoka, K.; Fukutani, Y.; Yamamoto, H. JOC 1985, 50, 4412.
6. Lehnert, E. K.; Sawyer, J. S.; Macdonald, T. L. TL 1989, 30, 5215.

Paul Knochel

Philipps-Universität Marburg, Germany

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