Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

Esterification and Etherification of Aliphatic Alcohols Enabled by Catalytic Strain-Release of Donor-Acceptor Cyclopropane

We herein disclose a highly efficient protocol for the esterification and etherification of alcohols, leveraging a Sc(OTf)3-catalyzed ring-strain release event in the meticulously designed, chromatographically stable mixed anhydrides or benzyl esters that incorporate an intramolecular donor-acceptor cyclopropane (DAC). This versatile method facilitates the straightforward functionalization of sugar, terpene, and steroid alcohols under mild acidic conditions, as showcased by the single-catalyst-driven, dual protection of sugar diol.

Cycloisomerization of π-Coupled Heteroatom Nucleophiles by Gold Catalysis: En Route to Regiochemically Defined Heterocycles

Since the dawn of millennium, catalytic gold chemistry is at the forefront to set off diverse organic reactions via unique activation of π-bonded molecules. Within this purview, cycloisomerization of heteroatom nucleophiles linked to a π-system is one of the well recognized chemistry for the construction of numerous heterocyclic cores. Though the rudimentary aspects of this transformation are reviewed by several groups in different timeline, a holistic view on regiochemistry of such reactions went largely overlooked. Hence, this account emphasizes the gold catalyzed regioselective cycloisomerization of structurally distinctive π-connected hetero-nucleophiles leading to different heterocycles documented in the last two decades. From an application perspective, this account also highlights those methodologies which find a role in the total synthesis of natural products. Wherever appropriate, mechanistic details and contributing factors for selectivity are also discussed.

Gold(i)-catalyzed C-glycosylation of glycosyl ortho-alkynylbenzoates: the role of the moisture sequestered by molecular sieves

C-Glycosylation of glycosyl ortho-hexynylbenzoates with allyltrimethylsilane or silyl enol ethers could proceed smoothly under the catalysis of Ph₃PAuNTf₂, wherein the moisture sequestered by the molecular sieves ensured the gold(i)-catalytic cycle.

Facile isomerization of silyl enol ethers catalyzed by triflic imide and its application to one-pot isomerization-(2 + 2) cycloaddition

A triflic imide (Tf₂NH) catalyzed isomerization of kinetically favourable silyl enol ethers into thermodynamically stable ones was developed. We also demonstrated a one-pot catalytic reaction consisting of (2 + 2) cycloaddition and isomerization. In the reaction sequence, Tf₂NH catalyzes both of the reactions.