Gold-Catalyzed Oxidative Ring Expansions and Ring Cleavages of Alkynylcyclopropanes by Intermolecular Reactions Oxidized by Diphenylsulfoxide

Optimizing P,N-bidentate ligands for oxidative gold catalysis: efficient intermolecular trapping of α-oxo gold carbenes by carboxylic acids

Steric Bulk or Conformation Control ? Optimization of P,N -bidentate ligands reveals the importance of conformation control in the development of highly efficient intermolecular trapping of reactive α-oxo gold carbene intermediates. While a pendant piperidine ring offers suitable steric bulk, fixing its conformation to provide better shielding to the highly electrophilic carbene center turned out to be crucial for the excellent reaction efficiency. A generally highly efficient and broadly applicable synthesis of carboxymethyl ketones from readily available carboxylic acids and terminal alkynes is developed under exceptionally mild reaction conditions.

Gold-catalyzed synthesis of glyoxals by oxidation of terminal alkynes: one-pot synthesis of quinoxalines

From terminal alkynes to glyoxals: Terminal alkynes can be oxidized under mild conditions by the use of an N-oxide in the presence of a gold catalyst. The intermediate glyoxal derivatives can be transferred in a one-pot procedure to substituted quinoxalines (see scheme).

Stereoselective preparation of cyclobutanes with four different substituents: total synthesis and structural revision of pipercyclobutanamide A and piperchabamide G

A general strategy was developed for the diastereo- and enantioselective synthesis of cyclobutanes with four different substituents. It consists of three transition metal-catalyzed reactions — a RhII-catalyzed cyclopropanation, a AgI-catalyzed regioselective and stereospecific ring expansion, and a RhI-catalyzed addition reaction. Structures of pipercyclobutanamide A and piperchabamide G were synthesized and revised.

Strained small rings in gold-catalyzed rapid chemical transformations

Gold-catalyzed reactions, which have been widely explored over the past several years, are powerful tools in organic synthesis to access complex molecular frameworks, and some corresponding excellent reviews have been reported. However, little attention has been paid to summarize the reactions of strained small-ring-containing molecules catalyzed by gold. This critical review mainly puts its emphasis on the recent progress in the field of gold-catalyzed transformations of cyclopropyl-, cyclopropenyl-, epoxy- and aziridinyl-containing molecules. The rapid construction of interesting building blocks in organic synthesis from strained small rings catalyzed by gold has been summarized in this review (106 references).

A flexible and stereoselective synthesis of azetidin-3-ones through gold-catalyzed intermolecular oxidation of alkynes

Chiral azetidin-3-ones could be easily prepared from chiral N -propargylsulfonamides, which in turn are readily accessible in excellent e.e. via chiral sulfinamide chemistry. Using t -butanesulfonyl as the protecting group avoids unnecessary deprotection and reprotection and allows its removal from the azetidine ring under acidic conditions.