The site-selective a-allylic alkylation of enones with alcohols via gold-triggered formation of nucleophilic allenoates by means of [3,3]-sigma- tropic rearrangements of propargylic carboxylates is reported. A range of a-alkylated enones is obtained in high yields in the presence of the gold complex [JohnPhosAu(ACN)]SbF6 (2 mol%) as the promot- ing agent. Examples of allylation/Friedel–Crafts al- kylation sequences are also provided, delivering densely functionalized dihydroindenes and dihydro- benzo[7]annulenes in a one-pot procedure in mod- erate yields. The role of the Brønsted acidity (i.e., pivalic acid) delivered during the reaction course in assisting the formation of carbocationic intermedi- ates is documented.
Elisabetta, M., Mario, D., Marco M., M., Assunta, D.N., Magda, M., Marco, B. (2016). Catalytic a-Allylation of Enones with Alcohols via [Gold(I)]- Mediated [3,3]-Sigmatropic Rearrangement of Propargylic Carboxylates. ADVANCED SYNTHESIS & CATALYSIS, 358, 1404-1409 [10.1002/adsc.201600113].
Catalytic a-Allylation of Enones with Alcohols via [Gold(I)]- Mediated [3,3]-Sigmatropic Rearrangement of Propargylic Carboxylates
MANONI, ELISABETTA;MASTANDREA, MARCO MICHELE;DE NISI, ASSUNTA;MONARI, MAGDA;BANDINI, MARCO
2016
Abstract
The site-selective a-allylic alkylation of enones with alcohols via gold-triggered formation of nucleophilic allenoates by means of [3,3]-sigma- tropic rearrangements of propargylic carboxylates is reported. A range of a-alkylated enones is obtained in high yields in the presence of the gold complex [JohnPhosAu(ACN)]SbF6 (2 mol%) as the promot- ing agent. Examples of allylation/Friedel–Crafts al- kylation sequences are also provided, delivering densely functionalized dihydroindenes and dihydro- benzo[7]annulenes in a one-pot procedure in mod- erate yields. The role of the Brønsted acidity (i.e., pivalic acid) delivered during the reaction course in assisting the formation of carbocationic intermedi- ates is documented.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
