Intramolecular Assistance of Electron Transfer. Oxidative Cleavage of the Carbon−Tin Bond of Tetraalkylstannanes
摘要:
Experimental and theoretical studies of intramolecular assistance by carbonyl groups and heteroatoms in the electron transfer driven cleavage of the carbon-tin bond of tetraalkylstannanes has been carried out. Carbonyl groups and heteroatoms (oxygen and nitrogen) in an appropriate position of tetraalkylstannane facilitate the electron transfer and selective cleavage of the carbon-tin bond. Although the coordination of the carbonyl groups and heteroatoms to tin was not detected in the neutral molecules, molecular orbital calculations indicate that the coordination of such groups to tin in the cation radical intermediate stabilizes the system and weakens the carbon-tin bond. These results offer striking examples of the intramolecular assistance of electron transfer driven reactions.
Intramolecular Assistance of Electron Transfer. Oxidative Cleavage of the Carbon−Tin Bond of Tetraalkylstannanes
摘要:
Experimental and theoretical studies of intramolecular assistance by carbonyl groups and heteroatoms in the electron transfer driven cleavage of the carbon-tin bond of tetraalkylstannanes has been carried out. Carbonyl groups and heteroatoms (oxygen and nitrogen) in an appropriate position of tetraalkylstannane facilitate the electron transfer and selective cleavage of the carbon-tin bond. Although the coordination of the carbonyl groups and heteroatoms to tin was not detected in the neutral molecules, molecular orbital calculations indicate that the coordination of such groups to tin in the cation radical intermediate stabilizes the system and weakens the carbon-tin bond. These results offer striking examples of the intramolecular assistance of electron transfer driven reactions.
Ketone dilithio alpha,beta- and alpha,beta'-dianions can be generated by a tin-lithium exchange reaction of the lithium enolate of beta-tributyltin substituted ketones. A chelation-aided approach, which employs beta-dichlorobutyltin substituted ketones and n-BuLi, is also useful for the generation of ketone alpha,beta-dianions having the Z-geometry at the alkene. The generated dianions can be transformed into substituted ketones by reaction with various carbon electrophiles. (c) 2005 Elsevier Ltd. All rights reserved.
NAKAHIRA, HIROYUKI;RYU, LHYONG;OGAWA, AKIYA;KAMBE, NOBUAKI;SONODA, NOBORU, ORGANOMETALLICS, 9,(1990) N, C. 277-280