[2179-89-7]  · C30H28N4  · Bis(1,3-diphenyl-2-imidazolidinylidene)  · (MW 444.58)

(electron-rich alkene; useful for formylation of arenes1)

Physical Data: mp 285 °C (dec).

Form Supplied in: prepared from 1,2-dianilinoethane and triethyl orthoformate.2

Handling, Storage, and Precautions: easily autoxidized; reagent that has oxidized may be upgraded by washing with CH2Cl2;2 store under dry nitrogen; reagent readily reacts with protic solvents, e.g. MeOH,1 and hydrolyzes in the presence of weak acid3 or basic1 media.

Arene Formylation.

Phenols treated with bis(1,3-diphenyl-2-imidazolidinylidene) in refluxing DMF give para-substituted cyclic aminals, which upon acid-catalyzed hydrolysis yield the corresponding aldehyde (eq 1).4,5 Multiple substitution can take place when an additional hydroxy or an acetamido moiety is present (eq 2).6 The reaction tolerates additional substituents on the phenolic ring, including alkyl, cycloalkyl, dialkylamino, chloro, acetamido, 2H-1,2,3-triazolyl, phenyl, and alkoxy groups;4-6 8-hydroxyquinoline-7-carbaldehyde was prepared in 52% yield.6

a-Substituted Aldehydes.

Addition of CH acidic compounds (e.g. PhCH2CO2Et or cyclopentanone) to bis(1,3-diphenyl-2-imidazolidinylidene) gives the a-substituted aminals, which upon hydrolysis provide entry into a-substituted aldehydes (eq 3).1,7


Treatment of a primary amine with bis(1,3-diphenyl-2-imidazolidinylidene) gives the aminoamidine,8 while dialkylamines and carboxamides react to give the 2-aminoimidazolidine8 or N-(2-imidazolidinyl)carboxamides,9 respectively (eq 4). Sulfonyl amides or phosphoric amides react to give either sulfonylamidines (78-95%) or phosphorylformamidines (83-100%).10

Homologs of 1,3-Diphenyl-2-imidazolidinone.

Treatment of solutions of bis(1,3-diphenyl-2-imidazolidinylidene) with O2, S8, or Se0 gives, respectively, the imidazolidinone (90%),7 thioimidazolidinone (85%),11 or the imidazolidineselenone (62%)12 (eq 5).

Carbene Complexes.

Palladium(II)13,14 and platinum(II)13 carbene complexes (trans) have been prepared from bis(1,3-diphenyl-2-imidazolidinylidene), as illustrated in eq 6.

1. (a) Carnduff, J. QR 1966, 20, 169. (b) Hoffmann, R. W. AG(E) 1968, 7, 754.
2. Wanzlick, H.-W. OS 1967, 47, 14.
3. Hagedorn, I.; Lichtel, K. E. CB 1966, 99, 524.
4. Hocker, J.; Giesecke, H.; Merten, R. AG 1976, 88, 151.
5. Hocker, J.; Giesecke, H. LA 1978, 345.
6. Hocker, J.; Giesecke, H. OS 1981, 60, 49.
7. Wanzlick, H. W.; Schikora, E. CB 1961, 94, 2389.
8. Hocker, J.; Merten, R. CB 1972, 105, 1651.
9. Hocker, J.; Merten, R. LA 1975, 1409.
10. Hocker, J.; Merten, R. LA 1978, 16.
11. Wanzlick, H. W.; Konig, B. CB 1964, 97, 3513.
12. Schonberg, A.; Singer, E.; Stephan, W. CB 1983, 116, 2068.
13. Cardin, D. J.; Cetinkaya, B.; Cetinkaya, E.; Lappert, M. F. JCS(D) 1973, 514.
14. Hiraki, K.; Onishi, M.; Sewaki, K.; Sugino, K. BCJ 1978, 51, 2548.

Steven J. Brickner

The Upjohn Company, Kalamazoo, MI, USA

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