Tandem Brønsted Acid Promoted and Nazarov Carbocyclizations of Enyne Acetals to Hydroazulenones
作者:Luz Escalante、Carlos González-Rodríguez、Jesús A. Varela、Carlos Saá
DOI:10.1002/anie.201205823
日期:2012.12.3
Ring the changes: Enyne acetals were easily converted into hydroazulene skeletons by a new and efficient metal‐free route involving a Brønsted acid promoted carbocyclization and a subsequent stereospecific Nazarov cyclization (see scheme). The versatility of this transformation also allowed assembly of interesting heteroaromatic tricyclic systems.
New Platinum-Catalysed Dihydroalkoxylation of Allenes
作者:María Paz Muñoz、María C. de la Torre、Miguel A. Sierra
DOI:10.1002/adsc.201000342
日期:2010.9.10
A new platinum‐catalysed dihydroalkoxylation of allenes is described to give aliphatic acetals by an unexpected attack of two molecules of methanol to the terminal carbon of the allene moiety. Deuteration experiments suggest an unprecedented formal 1,3‐dipolar addition of methanol to a zwitterionic platinum carbene as the key step. The first platinum‐catalysed intermolecular carbon‐based nucleophile