Organic Syntheses, CV 7, 129
Submitted by J. P. Barnier, J. Champion, and J. M. Conia
1.
Checked by Robert V. Stevens and Steven R. Angle.
1. Procedure
A.
1,2-Cyclobutanediol. A
2-L, three-necked, round-bottomed flask fitted with a
200-mL dropping funnel, a
mechanical stirrer, a
nitrogen-inlet tube, and a
reflux condenser equipped with a
calcium chloride drying tube is charged with
6.2 g (0.16 mol) of lithium aluminum hydride (Note
1) and (Note
2) and
200 mL of anhydrous diethyl ether (Note
3). The dropping funnel is charged with
42 g (0.48 mol) of 2-hydroxycyclobutanone (Note
4) and
150 mL of anhydrous diethyl ether. While the suspension of
lithium aluminum hydride is gently stirred under a nitrogen atmosphere, the solution of
2-hydroxycyclobutanone is added dropwise at a rate maintaining a gentle reflux. When the addition is complete, the mixture is heated at reflux for 1 hr. After the mixture has returned to room temperature,
200 mL of anhydrous diethyl ether is added. The gray reaction mixture is hydrolyzed by addition, in small parts, of a sufficient amount of wet
sodium sulfate (Note
5). The reaction mixture is filtered through a
sintered-glass funnel (porosity 3). The organic layer is decanted and dried over
sodium sulfate. The solid is extracted with anhydrous
tetrahydrofuran (Note
6) by means of a Soxhlet apparatus over a period of 24 hr. The combined organic layers are concentrated by distillation of the solvent with a
rotary evaporator. The yield of crude
cis- and trans-1,2-cyclobutanediol (ca. 50:50) is
34–40 g (
80–95%) (Note
7).
B.
Cyclopropanecarboxaldehyde. A
50-mL distilling flask equipped with a
receiver cooled to −20°C with a dry
ice–methanol bath is charged with
34 g (0.39 mol) of a crude mixture of both cis- and trans-1,2-cyclobutanediol and
10 μL of boron trifluoride butyl etherate (Note
8). The mixture is heated to 230°C with a
metal bath. Drops of liquid appear on the condenser, and the aldehyde and water distill into the receiver. The temperature of the distillate oscillates between 50 and 100°C. Each time the distillation stops,
5–10 μL of boron trifluoride butyl etherate is added to the distilling flask (Note
9). The distillate is transferred into a
separatory funnel and
sodium chloride is added. The organic layer is decanted and the aqueous layer is extracted three times with
25-mL portions of methylene chloride. The combined organic solution is dried over
sodium sulfate, and the solvent is removed by distillation through a
15-cm, helix-packed, vacuum-insulated column. The residue consists of practically pure
cyclopropanecarboxaldehyde,
17.5–21.6 g (
65–80%) (Note
10).
2. Notes
4. The checkers prepared
2-hydroxycyclobutanone by the Bloomfield procedure.
2 The submitters prepared it by their aqueous hydrolysis procedure.
3 This procedure was checked also and proceeds in quantitative yield as described.
3
5.
Sodium sulfate is mixed with water to form a thick slurry. It is added to the reaction mixture with vigorous stirring to obtain a good dispersion of the slurry in the medium. The added amount of wet
sodium sulfate is sufficient when the reaction effervescence ceases and the gray color of the mixture turns to yellow–white.
7. The crude
1,2-cyclobutanediol is dried by azeotropic distillation with anhydrous
benzene. The product is a mixture of
cis and
trans isomers (ca. 50:50) readily separable by gas chromatography on a
12-ft column containing 20% silicone SE 30 on Chromosorb W at 140°C.
cis-1,2-Cyclobutanediol (mp
12–13°C): IR (CCl
4) cm
−1: hydroxyl absorption at 3625 and 3580;
1H NMR (CCl
4) δ: multiplet at 1.98, multiplet at 4.20, and a singlet at 4.51 in a ratio 4:2:2, respectively.
trans-1,2-Cyclobutanediol (mp
72°C): IR (CCl
4) cm
−1: hydroxyl absorption at 3620:
1H NMR (CD
3COCD
3) δ: multiplet between 0.9 and 2.2, multiplet between 3.6 and 4.0, and singlet at 3.6 in a ratio of 4:2:2, respectively.
8.
Boron trifluoride butyl etherate, purchased from Fluka AG, is chosen for its convenient boiling point.
9. In a typical run
10 μL of boron trifluoride butyl etherate is added every 10–15 min over a period of 3–4 hr.
10. The crude product is more than 99% pure as shown by gas chromatography; IR (CCl
4) cm
−1: carbonyl absorption at 1730;
1H NMR (CCl
4) δ: doublet at 8.93, multiplet between 1.5 and 2.2, and a multiplet between 1.02 and 1.75 in the ratio 1:1:4, respectively. The product has bp
95–98°C (760 mm).
3. Discussion
This method of preparation of
cyclopropanecarboxaldehyde is an adaptation of that given by J. M. Conia and J. P. Barnier.
3 The various methods so far reported, which involve in the last step oxidation,
4 reduction,
5 or hydrolysis
6 of a suitable
cyclopropane derivative, are tedious or require expensive starting materials. The other routes involve the direct ring contraction of cyclobutane derivatives into
cyclopropanecarboxaldehyde starting from
cyclobutene oxide7 or from
2-bromo- or 2-tosyloxycyclobutanol.
8 The present procedure uses a particularly easy ring contraction, that of
1,2-cyclobutanediol, and it involves cheap, easily available starting materials. This method can be applied to symmetrical dialkylcyclobutane-1,2-diols, but it gives a mixture of two cyclopropyl carbonyl compounds from unsymmetrical diols.
Copyright © 1921-2002, Organic Syntheses, Inc. All Rights Reserved