W. Tully, L. Main, B. K. Nicholson
Jul 15, 2005
Citations
0
Influential Citations
8
Citations
Journal
Journal of Organometallic Chemistry
Abstract
Abstract Reaction of 1,5-diphenyl-3-(2-pyridyl)pentane-1,5-dione ( 5a ) with 2.5 moles of benzylpentacarbonylmanganese in petroleum spirit under reflux gives a small amount of the symmetric di-aryl-manganated product [1,5-diphenyl-κ C 2 -3-(2-pyridyl)pentane-1,5-dione-κ O 1 κ O 5 ]bis-(tetracarbonylmanganese) ( 7a ), but mostly [1,5-diphenyl-κ C 2 -3-(2-pyridyl-κ N )pentan-2-yl- κ C 2 -1,5-dione-κ O 1 κ O 5 ]tetracarbonylmanganesetricarbonylmanganese ( 6a ) which is manganated at only one aryl carbon [by Mn(CO) 4 ] but also [by Mn(CO) 3 with N and O coordination] at the methylene carbon adjacent to the Mn(CO) 4 -coordinated ketone carbonyl. The latter is a rare example of direct cyclomanganation at a saturated carbon and the only known case adjacent to a carbonyl group; the X-ray crystal structure of 6a is reported. With 3 moles of benzylpentacarbonylmanganese the yield of 6a remains unchanged but some trimanganation product [ 1 , 5 - diphenyl - κ C 2 ′ κ C 2 ‴ - 3 - ( 2 - pyridyl - κ N ) pentan - 2 - yl - κ C 2 - 1 , 5 - dione - κ O 1 κ O 5 ] tris - ( tetracarbonylmanganese ) ( 8a ) is formed, presumably from 7a . Routes to products are proposed and activating factors considered. 1,5-Di-(2-thienyl)-3-(2-pyridyl)pentane-1,5-dione ( 5b ) and its 3-thienyl isomer ( 5c ) similarly give 6a analogues [1,5-di-(2-thienyl-κ C 3 )-3-(2-pyridyl-κ N )pentan-2-yl-κ C 2 -1,5-dione-κ O 1 κ O 5 ]tetracarbonylmanganesetricarbonylmanganese ( 6b ) and [1,5-di-(3-thienyl-κ C 2 )-3-(2-pyridyl-κ N )pentan-2-yl-κ C 2 -1,5-dione-κ O 1 κ O 5 ]tetracarbonylmanganesetricarbonylmanganese ( 6c ). Also reported are the mono-cyclomanganation product [1-(2,6-dimethoxyphenyl)-3-(2-pyridyl-κ N )prop-2-en-2-yl-κ C 2 -1-one]tetracarbonylmanganese ( 16 ) and dicyclomanganation product [1-(2,5-dimethyl-3-thienyl-κ C 4 )-3-(2-pyridyl-κ N )prop-2-en-2-yl- κ C 2 -1-one-κ O ]bis-(tetracarbonylmanganese) ( 17 ) from reaction of the respective ( E )-1-aryl-3-(2-pyridyl)prop-2-en-1-ones (3-(2-pyridyl)chalcones), the first reported examples of enone metallation at the α-carbon via N -coordination by a β-2-pyridyl group.