Mechanism and origin of enantioselectivity in the Rh2(OAc)(DPTI)3-catalyzed cyclopropenation of alkynes. Academic Article

abstract

• The mechanism of cyclopropenations of alkynes with ethyl diazoacetate catalyzed by Rh2(OAc)4 and Rh2(OAc)(DPTI)3 (1) is studied by a combination of kinetic isotope effects and theoretical calculations. With each catalyst, a significant normal 13C KIE was observed for the terminal acetylenic carbon, while a very small 13C KIE was observed at the internal acetylenic carbon. These isotope effects are predicted well from canonical variational transition structures for cyclopropenations with intact tetrabridged rhodium carbenoids. A viable mechanism based on the recently proposed importance of a [2 + 2] cycloaddition on a tribridged rhodium carbenoid could not be identified. An explanation for the enantioselectivity with DPTI ligands is described.

authors

• Singleton, Daniel

author list (cited authors)

• Nowlan, D. T., & Singleton, D. A

citation count

• 50

complete list of authors

• Nowlan, Daniel T||Singleton, Daniel A

publication date

• January 2005

publisher

• American Chemical Society (ACS)  Publisher

published in

• Journal of the American Chemical Society  Journal

keywords

• Alkynes
• Cyclization
• Cyclopropanes
• Imidazoles
• Organometallic Compounds
• Rhodium
• Stereoisomerism

PubMed Central ID

• 15853322

Digital Object Identifier (DOI)

• 10.1021/ja0504441

start page

• 6190

end page

• 6191

volume

• 127

issue

• 17