Nov. 5, 195s [CONTRIBUTION
5837
3-METHYLENECYCLOBUTANONE
No. 2318
FROM THE
GATESAND CRELLINLABORATORIES OF CHEMISTRY,
CALIFORNIA INSTITUTE OF
TECHNOLOGY]
Small-ring Compounds.
XXI. 3-Methylenecyclobutanone and Related Compounds1
BY FREDERICK F. CASERIO,JR., AND JOHN D. ROBERTS RECEIVED MAY29. 1958 Experiments leading to the preparation of 3-methylenecyclobutanone are described. The desired substance was obtained only admixed with 3-methylcyclobutenone and this fact prevented evaluation of possible cross-ring ?r-type electronic interaction between the double bond and the carbonyl group.
in the preparation of 1,3-dimethylenecy~lobutane~ Introduction No definite evidence for cross-ring n-type elec- by reagents such as potassium permanganate, tron interaction was found in a study of 1,3-di- chromic acid and ozone would lead more directly methylenecyclobutane2 although LCAO calcula- to the desired product. Cnfortunately, the three tions suggest that such interaction might lead to a reagents named invariably led only t o uncharsmall but significant delocalization energy. Sub- acterizable products in poor yield. Conversion of the ketals XI1 and XI11 to I stitution of a more electronegative group isoelectronic with the methylene group for one of the by acidic hydrolysis was fraught with difficulties. methylene groups of 1,3-dimethylenecyclobutane Several combinations of solvents and acid catalysts would be expected to lead to a larger, and possibly were used. Solvent mixtures with water-miscible more easily observable, cross-ring n-type inter- organic components led to separation problems action. T o test this possibility, an attempt was which were made more difficult in the case of XI11 made to synthesize 3-methylenecyclobutanone (I) because of the production of ethanol as one of the since i t would possess the desired structural features products. Ketal exchange with acetone, which and appeared to be obtainable from intermediates has been very successful for the liberation of steroidal ketones from their k e t a l ~ ,gave ~ . ~ unidentialready available.2 fied condensation products. That compound I 0 was indeed produced by acid hydrolysis of XI11 9 was easily seen by following the course of the reaction with the aid of n.m.r. spectra. Figure 2 bshows the changes with time of the n.m.r. spectrum CH:! I of the organic phase of a heterogeneous, perchloric Synthesis of 3-Methylenecyclobutanone.-The acid-catalyzed hydrolysis of XIII. The n.m.r. synthesis of I started from 3-methylenecyclobutane- spectrum of pure XI11 shows the same type of carboxylic acid2s3 (11) and is outlined in Fig. 1. spin-spin splitting between the ring and vinyl The dimethylamide I11 was prepared as described hydrogens as observed with 1,3-dimethylenecyclopreviously2 and was converted to V in 70% yield butane.2 That this splitting was observed throughby oxidation with sodium metaperiodate and a out the hydrolysis indicates that the exocyclic catalytic amount of osmic acid in a modification double bond did not rearrange into the ring to any of the procedure of Johnson and Lemieux4 for the great extent under these conditions. In preparaoxidation of simple olefins. The keto-acid IV was tive experiments, hydrolyses of XI1 and XI11 also prepared by periodate oxidation in 70% yield were carried out as just described and were genand was converted into V in 22% yield by the erally followed by the n.m.r. or infrared spectrum action of thionyl chloride and dimethylamine. of the organic phase. When starting with X I I I , The ketals VI and VI1 were prepared in 69 and separation of the ketonic products from water and 98% yields, respectively, from I11 and the cor- ethanol proved troublesome and, although the responding hydroxyl compounds in the presence of ketonic products from XI1 were not contaminated acidic catalysts. Reduction of the ketals to the with ethylene glycol, they did contain some water. amino compounds VI11 and I X with lithium aluOn the basis of the n.m.r. and infrared spectra minum hydride proceeded smoothly in yields of 95 (Figs. 2 and 3), the product was a mixture of and 920/,, respectively. The N-oxides X and X I were prepared by treatment of the corresponding ketones I and XIV along with a small amount of amines with 10% hydrogen peroxide solution. a hydroxylic compound in ratios which varied Both N-oxides usually were obtained as sirups and from preparation to preparation. Separation of on pyrolysis afforded the methylene ketals XI1 and the two ketones could not be effected and matters XI11 in 61 and 7270 yields (based on VI1 and IX were not made easier by the fact that compound I rearranged quite rapidly to XIV a t slightly above as starting materials), respectively. It might appear that oxidation of the methylene room temperature. The rearrangement could be group of any of several of the intermediates used followed by both infrared and ultraviolet spectroscopy. Because of the ease of rearrangement of I, (1) Supported in part by the Petroleum Research F u n d of the distillations were carried out a t reduced pressure American Chemical Society. Grateful acknowledgment is hereby below room temperature. The ultraviolet spectra made t o the Donors of this Fund. of I and XIV are not reported in detail because of (2) F. F. Caserio, Jr., S. H. Parker, R. Piccolini and J. D. Roberts, TAISJOURNAL, 80,5507 (1958). thc uncertainty in the purity and composition -8
(3) D. E.Applequist and J . D. Roberts, ibid., 78,4012 (1950). (4) R. Pappo, D.S. Allen, Jr., R. U. Lemieux and W. S. Johnsou. J . OYE.Chcm., 21, 478 (1956).
(5) I,. H.Sarett, el al., THIS JOURNAL, 75, 429 (1053). (6) W.S. Johnson, el a!., ibid., 18, 6301 (1956).
5535
FREDERICK F. CASBRIO, JR.,
AND
J o m D ROBERTS
Vol.
so
observed rate sequence. It seems significant that the double bond of XI11 provides no apparent driving force to enhance the hydrolysis of XIII.
Experimental
.
3-Ketocyclobutanecarboxylic Acid (IV) -To a stirred, ice-cooled mixture of 300 ml. of ether, 300 ml. of water, 15 g. (0.134 mole) of I1 and 0.14 g. of osmic acid was added 60.5 g. (0.283 mole) of powdered j. sodium metaperiodate in small portions over 0.5 hr. The mixture became colorless after 5 hr. of stirring a t room temperature and the solid phase increased considerably. The mixture was allowed t o stir overnight and the ether layer was separated. The aqueous layer was filtered using suction and the filtrate was continuously extracted with ether for 18 hr. The filter cake was triturated with six 50ml. portions of chloroform. The combined organic extracts were dried over a mixture of anhydrous magnesium sulfate and carbon black, filtered and concentrated using a 30-cm. Vigreux column. The concenCHz CH? CII3 trate was almost black and was treated with decolorizing carbon, iiltered and the product allowed to crystallize. After two KO-] --/ + ,/crystallizations from benzene-n-hexane there was obtained 10.7 g. (70070) of RO 0 slightly yellow needles, m.p. 68-69 . Five recrystallizations from benzene-n-hexane XII, R , R = -(CHZ)ZI XI\' gave colorless needles, m.p. 69-70". X I I I , R = CZH5Anal. Calcd. for CaHeOa: C, 52.64; Fig. 1.-Synthesis of 1-inctliyle~iec~clubutallone. H , 5.31. Found: C, 52.74; H , 5.17. N,N-Dimethyl-3-ketocyclobutanecarboxamide (V) A. of the material obtained. I n ethanol, I appears N,N-Dimethyl-3-methylenecyclobutanecarboxamide to have a maximum a t 214 mp ( E ca. 1100-2000) From (III).-Starting with 200 ml. of ether, 200 ml. of water, and a very broad band a t 285 -I 30 mp ( E ca. 24) 31.3 g. (0.224 mole) of 111, 142 mg. of osmic acid and 109 g. while XIV has a maximum at 225 mp ( E ca. 7000- (0.508 mole) of sodium metaperiodate, the procedure for 9000). One ketone mixture gave an impure, preparation of IV was followed except that the continuous ether extraction required about 3 days. In a subsequent yellow 2,4-dinitrophenylhydrazone which had an preparation, chloroform proved to be a more efficient exultraviolet spectrum similar to dinitrophenyl- traction solvent. The black concentrate was distilled a t hydrazones of known unconjugated deriva- reduced pressure through a short Vigreux column and gave 21.9 g. (69%) of yellow product, b.p. 108-111" (1 mm.), tives.' Z 6 1.4850. ~ Repeated distillations a t 1 rnm. pressure reHydrogenation of the mixture of I and XIV gave nsulted in a colorless product. a single ketone XVI whose dinitrophenylhydrazone A n d . Calcd. for C7H1102N: C, 59.55; H , 7.86; N, was identical with that obtained from 3-methyl- 9.78. Found: C, 59.20; H , 7.79; rS, 9.82. cyclobutanone prepared by hydrolysis of the ketal B. From 3-Ketocyclobutanecarboxylic Acid (11).--.I soluXV from catalytic hydrogenation of XIII. tion of 1.8 g. (0.016 mole) of I1 and 4 g. (0.033 mole) of The difficulty experienced in attempts to separate thionyl chloride in 10 ml. of benzene was refluxed 0.5 hr. or] the ketones I and XIV from the ethanol i n the a steam-bath and then evaporated to about 5 rnl. To thc solution was added slowly 4 g. (0.09 mole) of rlihydrolysis of XI11 suggested use of the cyclic ice-cooled methylamine dissolved in 10 rnl. of benzene. After the acldiketal XI1 in place of X I I I . This substitution tion was completed, 100 ml. of ether was added and the preactually introduced a more serious difficulty be- cipitate of dimethylamine hydrochloride removed by filtracause XI1 hydrolyzed exceedingly slowly and the tion. The ether solution was concentrated using a 30-cin. Vigreux column and the dark-red residue was distilled three resulting I largely rearranged t o XIV bcfore even times through a micro apparatus giving 0.5 g. (23%) of 257, of the cyclic ketal had hydrolyzed. The product, b.p. 112-120' (1-2 mm.), ~ Z * Z * ~ D1.4860. The inextent of rearrangement for the heterogeneous frared spectrum of this product was superirnposable on that hydrolysis mixtures was determined with the aid of the product by method A above. N,N-Dimethyl-3-ketocyclobutanecarboxamide Ethylene of n.m.r. and infrared spectra taken on aliquots Ketal (VI).-A solution of 20 g. (0.3 mole) of dry ethylene of the organic phase at various times. Qualita- glycol, 4.0 g. (0.028 mole) of V, 4.2 g. (0.028 mole) of ethyl tively, the rates of hydrolysis for the ketals in- orthoformate and 0.1 g. of p-toluenesulfonic acid (monohycreased in the order XI1 XI11 < XV, 13 hours drate) was allowed t o stand overnight a t room temperature. The acid catalyst was neutralized by the addition of being required for about 36% hydrolysis of X I I , several small pellets of potassium hydroxide and the solution about 10 hours for 50% hydrolysis of XI11 and was diluted with 50 ml. of water. The aqueous solution was about 2 hours for complete hydrolysis of XV. extracted with five 15-ml. portions of chloroform. The The differences in the strain energies of the starting extracts were combined, dried momentarily over anhydrous sulfate, filtered and the solvent distilled from a ketal and ketonic products might account for the magnesium steam-bath through a 30-cm. Vigreux column. The residue was distilled and gave 3.0 g. (61%) of product, b.p. (7) J. D. Roberts and C. Green, TEISJOURNAL, 68, 214 (1946).
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il
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