Construction of cyclic enones via gold-catalyzed oxygen transfer reactions

• Leping Liu,
• Bo Xu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2011, 7, 606–614, doi:10.3762/bjoc.7.71

• case, the gold catalyst exhibited a dual role, namely the activation of alkyne and carbonyl moieties. Yamamoto and co-workers attempted to utilize their protocol to build five-membered cyclic enones, however, when they employed alkynyl ketone 9 as the substrate, the gold catalyst did not show good

• reported gold-catalyzed cyclizations to cyclohexenones 17, employing terminal 1,6-diynes 16 as substrates in the presence of a Brønsted acid and 1 equiv of water (Scheme 12) [48]. None of the desired products were obtained in the absence of the gold catalyst, the Brønsted acid or water. Interestingly, when

• the diacid 1,6-diyne (R1 = R2 = COOH) was employed in the reaction, only the esterified product (R1 = R2 = COOMe) was isolated, albeit in low yield. The authors also carried out this gold-catalyzed transformation in an ionic liquid [49]. This modification enabled the separation of the gold catalyst

Gold-catalyzed regioselective oxidation of terminal allenes: formation of α-methanesulfonyloxy methyl ketones

• Yingdong Luo,
• Guozhu Zhang,
• Erik S. Hwang,
• Thomas A. Wilcoxon and
• Liming Zhang

Beilstein J. Org. Chem. 2011, 7, 596–600, doi:10.3762/bjoc.7.69

• desired product was observed in the absence of a gold catalyst (entry 10). With the optimized reaction conditions established (Table 1, entry 8), the scope of this chemistry was studied. As shown in Table 2, remote functional groups were readily tolerated. For example, good yields were obtained in the

A gold-catalyzed alkyne-diol cycloisomerization for the synthesis of oxygenated 5,5-spiroketals

• Sami F. Tlais and
• Gregory B. Dudley

Beilstein J. Org. Chem. 2011, 7, 570–577, doi:10.3762/bjoc.7.66

• encouraging results. Other gold catalysts and solvents were screened, with the best results being achieved with a higher catalyst loading of gold(I) chloride in methanol (Table 1, entry 10). The need for higher catalyst loading is tentatively ascribed to some form of instability of the gold catalyst in