The chemistry of small ring compounds IX. The base catalysed reactions of cyclopropanecarbaldehyde and cyclobutanecarbaldehyde.

Tetrahedron Letters~0.46,pp. 4521-4524, 1967. Pergamn Press Lid.

Printedin GreatBritain.

THE CIUEKISTRYOF SMALL RING COMPOUNDS IX (1). TRE BASE CATALYSED REACTIOBS OF CYCLOPROPAEECARJ3ALDEKYDE AND CYCLOBUTAEECARBALD~E*.

F.P.B. van aer Maeden, H. Steinberg and Th.J. de Boer Laboratory for Organic Chemistry, University of Amsterdam, Nieuwe Achtergracht 129, Amsterdam, The Netherlands. (Received in UK 15 July l.967)

Because of the different s-character of the C-H bona of the cyclopropane ring (SP2*28) and of the cyclobutane ring (sp') (2) , it was of interest ?o investigate whether cyclopropenecarbaldehyde 1 and cyclobutanecarbaldehyde _1 undergo the alaol and/or Canniezaro reaction. Reaction of cyclopropanecsxbaldehyde 1 with an excess of sodiVumhydroxide for 17 hours at 80°C leads exclusively to an equimolar amount of cyclopropanecarboxylic acid 2 and cyclopropylmethanol 2. On the other hand cyclobutaae0

2-H 2

*

F%Tr

H-

COOH HO 0

H +

$,f' the forthcoming thesis of F.P.B. van der hFseden.

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45s

No.46

carbaldehyde 3 gives under similar conditions after 42 hours

cyclobutylme-

than01 S, cyclobutanecarboxylic acid p, cyclobutyl-[l-(l-hydroxymethyl)cyclobutyll-methanol 5 and l-(cyclobutylhydroxymethyl)cyclobutanecarboxylic acid 1.

4

8 I. HO

OH

4-

CHpOH

H

e(346)

I(4551

In the older work of Perkin and Coleman (3) it wae suggested that only the products 2 ena p are formed. The products 6 and 1 can arise by a Cannizzaro reaction between two molecules of 2 or by a crossed Cannizzaro reaction with 4, which yields also g aa p. We were unable to isolate the primarily formed aldol 2 from the remaining few percents of unidentified reaction products. The infrared spectrum of 5 (liq. film) shows the strong associated OH-band between 3600 - 3100 cm"

and CH methylene bands in the 2900 cm"

region. The

NMR spectrum (CDC13) displays a singlet at 6 = 4.1 (OH, variable with concentration), a singlet at 6 = 3.75 (-0CH2), a doublet centred at 6 = 3.6 (>CHO-) and broad absorption bends between 6 = 1.2 - 2.9 (cyclobutyl protons). The infrared spectrum of 1 (KBr) has the characteristic OH, CH and C=O absorption bands. The Nb?R spectrum of 1 ((CD3)2CO) shows a broad band at S = 7.1 (COOH), a doublet centred at 6 = 3.8 (XXO-)

and a broad signal

between 6 = 1.4 - 2.8 (cyclobutyl protons). At 8O*C, the sodium methoxide catalysed reaction of cyclopropanecarbaldehyda 1 in methanol yielded after 96 hours a mixture of cyclopropylmethsnol 2, methylcyclopropsnecarboxylate lo, cyclopropanecarbaldehyde dimethylacetal 11 in a ratio 2:2:l.approximately and a minor amount of cyclopropylmethyl

cycle-

450

~0.46

propanecarboxylate 12 presumably arising by trenseeterification between Iana

.!J-”

d‘

CH30e

H CH30H

;r

2(36k)

1

Is(36$)

+ L'(lM)

1_2(4S)

The infrared spectrum of 12 (CC141 reveals strong bands at 1720 cm" 1170

and

1200

ml-

(C-O).

(C=O),

The NMR spectrum (Ccl41 shows a doublet centred at

6 = 3.9 (0(X2) and a broad signal between 6 = 0.1 - 0.9 (cyclopropyl protons) with peak areas in the ratio I:5. The formation of the dimethylacetal fi ie more difficult to explain. There is no doubt aa to its structure because the infrared spectrum of JI_ (Ccl41 displays maxima at 3100 and 3000 cm-' (cyclopropyl CH) and at 2820 cm*' (OCH) whereas OH and C=O absorptiona are abeent. The NMR spectrum of G

(CC14)

shows a doublet centred at 6 = 4.1 (H-C/'-), a singlet at 6 = 3.3 (OCH3> and 'obroad multiplet between S = 0.2 - I.3 (cyclopropyl protons) with peak areas in the ratio 1:6:5. Analysis calo. for C6H1202:C 62.04; H 10.41; 0 27.55. Found C 61.9; H 10.4; 0 27.5. A "normal" synthesis of 11 wae achieved through reaction of oyolopropanecarbaldehyde with a small amount of hydrogen chloride in methanol for two hours at 80°C. Yield 65s talc. on recovered aldehyde. Two byproducts were formed which were identified ae 1,1,4-trimethoxybutane (5%) and 4-chloro-1,1-dimethoxybutane (25s) by elemental aualyais, infrared and NAB spectral data. The mechanism of acetal formation -an exceptional process in alkaline mediumis under investigation.

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REFERXNCES I. Preceeding papers: Part VI. S.E. Schaafsma, H. Steinberg and 7h.J. de Boer, Rec. Trav. Chim., g,

651 (1967); Part VII. J. Bus, H. Steinberg and

Th.J. de Boer, Tetrahedron Letters, La,, 1979 (1966); Part VIII. J.Th. van Wijnen, I-I. Steinberg end Th.J. de Boer, Tetrahedron in press. 2. B.J. Cram, Fundamentals of Carbanion Chemistry, Academic Press, mew YorkLondon, 1965, p. 48. 3. H.G. Coleman end W.H. Perkin, J. Chem. Sot., a,

238 (1887).