Isomerization gold chloride

The substitution of propargyhc alcohols by amides gives propargyUc amides which can be isomerized into allenyl amides and cyclized into oxa-zoles in the presence of catalytic amounts of gold chloride (Scheme 49). The catalytic transformations can be performed by introduction of aU the starting products including the catalysts at the beginning of the reaction, but better yields are obtained when AuCls is introduced after completion of the rutheniiun-catalyzed reaction [106]. 

Acetylenic ketones are viable substrates as well for gold-catalyzed cyclizations to furans. Whereas alk-3-yn-l-ones readily cyclize to substituted furans in the presence of gold(I) or gold(III) chloride (possibly via isomerization to a-allenyl ketones see Section 5.2), the corresponding transformation of alk-4-yn-l-ones takes place in the presence of the cationic gold catalyst generated in situ from PhsPAuCl and AgOTf in toluene (Scheme 4-83). The cyclization is accelerated by... 

---