A series of pentacarbonyl(2-oxacyclopentylidene)chromium (5a-f) were reacted with N,N-dimethylformamide dimethyl acetal (DMF-DMA), resulting in the pentacarbonyl(2-oxa-5-[(N,N-dimethylamino)methylidenelcyclopentylideneJchromium (6a-f) and the unexpected pentacarbonyl(2-oxa-5-(cyclopropylmethylidene)cyclopentylidene)chromium (7a-d). Open chain Fischer type carbene complexes (CO)5CrC(OCH3)CH2R1 (1a-d) also react easily with DMF-DAA (2a-d). When R1 = H, the carbene complex (CO)5CrC(OCH3)CHCHN(CH3)2 is formed in high yield; however, when R1 = alkyl, the reaction products are dialkoxy complexes (CO)5CrC(OCH3)OR2 (4a-d), in which the OR2 group comes from the DMF-DAA. The mechanisms of the above reactions are elucidated. The cyclopropyl ring present on compounds 7a-d arises from a contraction of the five membered ring of complexes 5a-d due to the breaking of the bond between the carbene carbon atom and the α-carbon atom. The same mechanism explains the formation of dialkoxy complexes 4a-d from complexes 1b-d. In the case of the reaction of the complex (CO)5CrC(OCH3)CH2CH2CH2CH3 (1d) with N,N-dimethylformamide dineopentyl acetal (2d), the intermediary formation of an enamine derivative has been demonstrated. Moreover the reaction of pentacarbonyl(2-oxa-4,4-dimethylcyclopentylidene)-chromium (5g) with DMF-DMA (2a) allowed the isolation of 2,2-dimethylcyclopropanecarbaldehyde (characterized as the (2,4-dinitrophenyl)hydrazone)

Baldoli, C., Lattuada, L., Licandro, E., Maiorana, S., Papagni, A. (1993). Reaction of Fischer Type Chromium Carbene Complexes with N,N-Dimethylformamide Dialkyl Acetals (DMF-DAA): An Unexpected Carbon-Carbon Bond Breaking. ORGANOMETALLICS, 12(8), 2994-3000 [10.1021/om00032a023].

Reaction of Fischer Type Chromium Carbene Complexes with N,N-Dimethylformamide Dialkyl Acetals (DMF-DAA): An Unexpected Carbon-Carbon Bond Breaking

PAPAGNI, ANTONIO
1993

Abstract

A series of pentacarbonyl(2-oxacyclopentylidene)chromium (5a-f) were reacted with N,N-dimethylformamide dimethyl acetal (DMF-DMA), resulting in the pentacarbonyl(2-oxa-5-[(N,N-dimethylamino)methylidenelcyclopentylideneJchromium (6a-f) and the unexpected pentacarbonyl(2-oxa-5-(cyclopropylmethylidene)cyclopentylidene)chromium (7a-d). Open chain Fischer type carbene complexes (CO)5CrC(OCH3)CH2R1 (1a-d) also react easily with DMF-DAA (2a-d). When R1 = H, the carbene complex (CO)5CrC(OCH3)CHCHN(CH3)2 is formed in high yield; however, when R1 = alkyl, the reaction products are dialkoxy complexes (CO)5CrC(OCH3)OR2 (4a-d), in which the OR2 group comes from the DMF-DAA. The mechanisms of the above reactions are elucidated. The cyclopropyl ring present on compounds 7a-d arises from a contraction of the five membered ring of complexes 5a-d due to the breaking of the bond between the carbene carbon atom and the α-carbon atom. The same mechanism explains the formation of dialkoxy complexes 4a-d from complexes 1b-d. In the case of the reaction of the complex (CO)5CrC(OCH3)CH2CH2CH2CH3 (1d) with N,N-dimethylformamide dineopentyl acetal (2d), the intermediary formation of an enamine derivative has been demonstrated. Moreover the reaction of pentacarbonyl(2-oxa-4,4-dimethylcyclopentylidene)-chromium (5g) with DMF-DMA (2a) allowed the isolation of 2,2-dimethylcyclopropanecarbaldehyde (characterized as the (2,4-dinitrophenyl)hydrazone)
Articolo in rivista - Articolo scientifico
N,N-DIMETHYLFORMAMIDE DIALKYL ACETALS (DMF-DAA), C-C bond breaking, Cyclic carbene complexes
English
1993
12
8
2994
3000
none
Baldoli, C., Lattuada, L., Licandro, E., Maiorana, S., Papagni, A. (1993). Reaction of Fischer Type Chromium Carbene Complexes with N,N-Dimethylformamide Dialkyl Acetals (DMF-DAA): An Unexpected Carbon-Carbon Bond Breaking. ORGANOMETALLICS, 12(8), 2994-3000 [10.1021/om00032a023].
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/32350
Citazioni
  • Scopus 11
  • ???jsp.display-item.citation.isi??? 12
Social impact