Cyclopropanone
Cyclopropanone is an organic compound with molecular formula C3H4O consisting of a cyclopropane carbon framework with a ketone functional group. The parent compound is labile with melting point -90°C and has been prepared by reaction of ketene with diazomethane at -145°C [1] [2]. Derivatives of cyclopropanone are of some interest to organic chemistry [3].
In organic synthesis the use of cyclopropanone itself is substituted by that of synthons like acetals cyclopropanone ethyl hemiacetal [4] or Cyclopropanone ethyl trimethylsilyl acetal [5]
Derivatives
Cyclopropanones are intermediates in the Favorskii rearrangement with cyclic ketones where carboxylic acid formation is accompanied by ring-contraction.
An interesting feature of cyclopropanones is that they react as 1,3-dipoles in cycloadditions for instance with cyclic dienes such as furan [6] [7]. An oxyallyl intermediate or valence tautomer (formed by cleavage of the C2-C3 bond) is suggested as the active intermediate or even a biradical structure (compare to the related trimethylenemethane).
Cyclopropanone tautomeric structures
Experimental evidence is not conclusive. Other reactions of cyclopropanones take place through this intermediate. For instance enantiopure (+)-trans-2,3-di-tert-butylcyclopropanone racemizes when heated to 80°C [8].
An oxyallyl intermediate is also proposed in the photochemical conversion of a 3,5-dihydro-4H-pyrazole-4-one with expulsion of nitrogen to an indane [9]:
2,3-Dimethyl-2,3-diphenylcyclopropanone intermediate in photolysis
In this reaction oxyallyl intermediate A, in chemical equilibrium with cyclopropanone B attacks the phenyl ring through its carbocation forming a transient cyclohexadiene C (with UV trace similar to isotoluene) followed by rearomatization. The energy difference between A and B is 5 to 7 kcal/mole.
See also
- Other cyclic ketones: cyclobutanone, cyclopentanone, cyclohexanone
- Other cyclopropane derivatives: cyclopropene, cyclopropenone
References
- ↑ Preparation and characterization of cyclopropanone, methylcyclopropanone, 2,2-dimethylcyclopropanone and tetramethylcyclopropanone N. J. Turro and W. B. Hammond Tetrahedron Volume 24, Issue 18, 1968, Pages 6017-6028 doi:10.1016/S0040-4020(01)90985-8
- ↑ Cryochemical synthesis and molecular energetics of cyclopropanone and some related compounds E. F. Rothgery, R. J. Holt, H. A. McGee, , Jr. J. Am. Chem. Soc.; 1975; 97(17); 4971-4973. doi:10.1021/ja00850a034
- ↑ Cyclopropanones Nicholas J. Turro Acc. Chem. Res.; 1969; 2(1); 25-32. doi:10.1021/ar50013a004
- ↑ Organic Syntheses, Coll. Vol. 7, p.131 (1990); Vol. 63, p.147 (1985). [Link http://www.orgsynth.org/orgsyn/pdfs/CV7P0131.pdf]
- ↑ Datasheet commercial supplier Link
- ↑ Cyclopropanones. XII. Cycloaddition reactions of cyclopropanones Nicholas J. Turro, Simon S. Edelson, John R. Williams, Thomas R. Darling, Willis B. Hammond J. Am. Chem. Soc.; 1969; 91(9); 2283-2292. doi:10.1021/ja01037a018
- ↑ Cyclopropanones. XVII. Kinetics of the cycloaddition reaction of cyclopropanones with 1,3-dienes Simon S. Edelson, Nicholas J. Turro J. Am. Chem. Soc.; 1970; 92(9); 2770-2773. doi:10.1021/ja00712a030
- ↑ Thermal reactions of a cyclopropanone. Racemization and decarbonylation of trans-2,3-di-tert-butylcyclopropanone Frederick D. Greene, David B. Sclove, Jose F. Pazos, Ronald L. Camp J. Am. Chem. Soc.; 1970; 92(25); 7488-7488. doi:10.1021/ja00728a051
- ↑ First Direct Detection of 2,3-Dimethyl-2,3-diphenylcyclopropanone Andrey G. Moiseev, Manabu Abe, Evgeny O. Danilov, and Douglas C. Neckers J. Org. Chem.; 2007; 72(8) pp 2777 - 2784; (Article) doi:10.1021/jo062259r