Cyclopropenes, Stetter reaction

Scheme 7.33 NHC-catalyzed asymmetric intermolecular Stetter reaction of aromatic aldehydes and cyclopropenes reported by Glorius.

Later, the group used cyclopropenes 49 as acceptors for the intermolecular Stetter reaction. In the presence of electron-rich triazolium salt H4, a variety of aldehydes and cyclopropenes worked well and afforded the acyl-cyclpropanes 50 in up to 98% yield with up to 96% enantiomeric excess (Scheme 20.24). 

In 2011, Glorius and co-workers [61] first reported the Stetter reaction of aldehydes 54 with cyclopropenes 55. The acylation products 56 were obtained in moderate to good yield with excellent diastereocontrol (Scheme 7.41). 

The intermolecular Stetter reaction of benzaldehyde and cyclopropene, catalysed by NHCs, has been modelled using DFT. " The roles of water and of bases such as DBU in affecting the free energy and controlling the diastereomeric ratio are examined. 

---