The diastereospecific formation of β-amino-α-cyclopropenyl phosphonates has been achieved
in moderate yields from the cyclopropenation of 1-alkynes with dialkyl α-diazophosphonates.
The reaction was performed by using a combined catalyst consisting of Cu(MeCN)4BF4 and BF3·Et2O as additive in dichloromethane at 40 °C. A possible mechanism for the reaction has
been proposed to explain the origin of the activation and the asymmetric induction.
This method provides a versatile approach to β-amino-α-cyclopropenylphosphonates containing
a quaternary stereogenic center with good efficiency and diastereoselectivity.
Key words
cyclopropenation - α-diazophosphonates - asymmetric synthesis - cyclopropenylphosphonates
- Cu(MeCN)
4BF
4/BF
3·Et
2O