Combining oxidative N-heterocyclic carbene catalysis with click chemistry: a facile one-pot approach to 1,2,3-triazole derivatives.

A combination of the oxidative N-heterocyclic carbene catalysis and click chemistry has been explored for the direct, one-pot synthesis of 1,2,3-triazole derivatives from aromatic aldehydes. This procedure was found to be very efficient and a variety of 1,2,3-triazole derivatives could be accessed through their corresponding propargyl esters in moderate-to-good yields under mild conditions.

N-heterocyclic carbene catalysed aerobic oxidation of aromatic aldehydes to aryl esters using boronic acids.

The organocatalytic behavior of N-heterocyclic carbenes in the aerobic oxidation of aromatic aldehydes to esters with boronic acids has been explored. This transition metal-free protocol allows access to a wide variety of aromatic esters in good to excellent yields under mild reaction conditions.

Fragmentation of nitrone triflates to 9-membered rings.

A new fragmentative rearrangement of nitrone derivatives to form 9-membered rings is reported. The fragmentations are triggered when nitrones are treated with triflic anhydride; a C-C bond antiperiplanar to the cleaving N-O bond is activated either by an oxygen lone pair or by an electron-rich aromatic ring. In the former case, further cyclization of the 9-membered intermediate leads to a rearranged condensed ring system, but when triggered by arenes, 9-membered ring amides are isolated.

A ring-closing metathesis approach toward formal total synthesis of (+)-diplodialide A.

An asymmetric formal total synthesis of diplodialide A 1a has been achieved starting from methyl acetoacetate 6 and (R)-3-buten-2-ol 7. The macrocyclic ring core of (+)-diplodialide A 1a was constructed, in an excellent yield, by using a ring-closing metathesis strategy.