Palladium-catalyzed divergent reactions of 1,6-enyne carbonates: synthesis of vinylidenepyridines and vinylidenepyrrolidines.

A method for preparing five- or six-membered heterocyclic compounds from enyne carbonates via palladium catalysis was developed. Enyne carbonates were transformed into 3-vinylidene-1-tosylpyridines 2 in the presence of PdI(2) as the catalyst. Using Pd(dba)(2) as the catalyst, 3-vinylidene-1-tosylpyrrolidines 3 were obtained. Further functionalizations of compounds 3 were carried out in a one-pot manner.

Copper-catalyzed direct thiolation of azoles with aliphatic thiols.

Cu(II)-catalyzed direct thiolation of azoles with thiols is described via intermolecular C-S bond formation/C-H functionalization under oxidative conditions. Both aryl thiols and aliphatic thiols are used as coupling partners, and furnished the thiolation products in moderate to good yields. The reaction is compatible with a wide range of heterocycles including oxazole, thiazole, imidazole and oxadiazole.

Pd(0)-catalyzed [1,5]-sigmatropic hydrogen shift of propargylic esters toward substituent naphthylamines.

A novel and convenient carboannulation method for the synthesis of highly substituted naphthylamine derivatives has been developed though a Pd(0)-catalyzed [1,5]-sigmatropic hydrogen shift and cyclization reaction of propargyl esters.

Electrophilic carbocyclization of aryl propargylic alcohols: a facile synthesis of diiodinated carbocycles and heterocycles.

Diiodinated carbocycles and oxygen heterocycles can be readily synthesized by electrophilic carbocyclization of aryl propargylic alcohols in moderate to good yields under mild conditions. The resulting diiodide can be further exploited by subsequent oxidizing and coupling reactions. Both the iodine anion and cation generated from I(2) are used effectively. The presence of a trace amount of water is essential for this electrophilic cyclization.

Novel carbon-carbon bond formation from propargylic alcohols and olefin toward five-membered heterocyclic rings catalyzed by AgSbF6.

A mild and direct process for C-C bond formation from propargylic alcohols and olefin has been developed in the presence of a silver catalyst. In this reaction, trace amounts of water were necessary and allene alcohols 2 and 1,3-dienes 3 were obtained selectively.

Acid-catalyzed skeletal rearrangement of epoxy alkynes: a fast access to highly functionalized allenes.

The acid-catalyzed reaction of epoxy alkyne involves an epoxide ring-opening attacked by pi-alkyne, leading to a semipinacol-type rearrangement. In this process, a type of carbon-carbon 3,3-migration of the alkyne system has been discovered, which is promoted both by epoxide inducing and hydroxide promoting. This transformation enables the fast synthesis of allenes in mild conditions.

Gold-catalyzed tandem cyclization/Friedel-Crafts type reactions toward furan derivatives.

A simple and convenient synthetic approach to furan derivatives 4 has been developed via gold-catalyzed tandem cyclization/Friedel-Crafts type reactions.

PtCl2-catalyzed tandem triple migration reaction toward (Z)-1,5-dien-2-yl esters.

A novel method for the selective synthesis of (Z)-1,5-dien-2-yl esters has been developed though Pt(II)-catalyzed tandem 1,2-acyl and 1,2-hydride migration, along with an allyl migration reaction of propargylic carboxylates with electronically unbiased internal alkynes. The unusual selectivity of 1,2-acyloxy migration was realized.