Org. Synth. 1954, 34, 54
DOI: 10.15227/orgsyn.034.0054
[1-Oxaspiro[2.5]octane-2-carboxylic acid, ethyl ester]
Submitted by Richard H. Hunt, Leland J. Chinn, and William S. Johnson1.
Checked by N. J. Leonard and F. P. Hauck, Jr..
1. Procedure
The reaction is conducted in a 500-ml. round-bottomed three-necked flask to which are attached (ground-glass joints) a rubber slip-sleeve-sealed wire stirrer, a thermometer, and a pressure-equalized dropping funnel. The top of the dropping funnel is connected to a system for exhausting and filling with nitrogen (p. 133). The apparatus is flame-dried at reduced pressure, and the flask is charged with 14.50 g. (0.148 mole) of freshly distilled cyclohexanone and 18.15 g. (0.148 mole) of freshly distilled ethyl chloroacetate. A solution of 6.0 g. (0.153 g. atom) of potassium in 125 ml. of dry tert-butyl alcohol (Note 1) and (Note 2) is introduced into the dropping funnel, and the system is exhausted and filled with nitrogen. The flask is cooled with an ice bath, stirring is commenced, and the solution of potassium tert-butoxide is added from the dropping funnel over a period of about 1.5 hours, the temperature of the reaction mixture being maintained at 10–15°. After the addition is complete, the mixture is stirred for an additional 1–1.5 hours at about 10°. Most of the tert-butyl alcohol is removed by distillation from the reaction flask at reduced pressure (water aspirator) and a bath temperature of 100°. The oily residue is taken up in ether. The ether solution is washed with water, then with saturated aqueous sodium chloride solution, and is finally dried over anhydrous sodium sulfate. The residue obtained on evaporation of the ether is distilled through a 6-in. Vigreux column to give 22.5–26.0 g. (83–95% yield) of colorless glycidic ester, b.p. 134–137°/21 mm., 147–152°/30 mm., n25D 1.4568–1.4577 (Note 3).
2. Notes
1. The preparation of potassium tert-butoxide is carried out according to a procedure already described (p.132). Particular attention should be paid to the precautions in handling potassium.
2. The tert-butyl alcohol may be dried over sodium (p.134). Scrupulously dry tert-butyl alcohol may be prepared by distilling alcohol thus treated from calcium hydride (about 1 g./4 l.), obtainable from Metal Hydrides, Inc.
3. This material is of satisfactory quality, as shown by its conversion to solid derivatives in good yield.2
3. Discussion
Ethyl β,β-pentamethyleneglycidate has been prepared in 65% yield by the condensation of cyclohexanone with ethyl chloroacetate in the presence of sodium ethoxide,3,4 and in 50% yield in the presence of sodium in xylene.4,5 The present procedure employs potassium tert-butoxide as the condensing agent.2

References and Notes
  1. University of Wisconsin, Madison, Wisconsin.
  2. Johnson, Belew, Chinn, and Hunt, J. Am. Chem. Soc., 75, 4995 (1953).
  3. Darzens and Lefebure, Compt. rend., 142, 714 (1906); Rodinov and Kiseleva, Izvest. Akad. Nauk S.S.S.R., Otdel. Khim. Nauk, 1952, 278 [C. A., 47, 3300 (1953)]; Akad. Nauk S.S.S.R., Inst. Org. Khim., Sintezy Org. Soedinenii, Sbornik, 2, 57 (1952) [C. A., 48, 570 (1954)].
  4. Chiurdoglu, Mathieu, Baudet, Delsemme, Planchon, and Tullen, Bull. soc. chim. Belges, 65, 664 (1956).
  5. Lunt and Sondheimer, J. Chem. Soc., 1950, 2957; Martynov, Zhur. Obshchei Khim., 23, 2006 (1953) [C. A., 49, 3124 (1955)].

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

ether (60-29-7)

Cyclohexanone (108-94-1)

sodium chloride (7647-14-5)

sodium sulfate (7757-82-6)

nitrogen (7727-37-9)

sodium (13966-32-0)

sodium ethoxide (141-52-6)

Ethyl chloroacetate (105-39-5)

potassium (7440-09-7)

xylene (106-42-3)

tert-butyl alcohol (75-65-0)

Ethyl β,β-pentamethyleneglycidate,
1-Oxaspiro[2.5]octane-2-carboxylic acid, ethyl ester (6975-17-3)

calcium hydride (7789-78-8)

potassium tert-butoxide (865-47-4)