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The divalent samarium triflate salt does not react with CO2 or water, but does react with traces of O2 or N2O to form a tetrameric bis-oxo samarium motif. The reaction with O2 is a 4e− reductive cleavage where the electrons are coming from four different samarium centers. This highlights a rare synergistic effect for cleaving O2, which has no precedent in divalent lanthanide complexes. Additionally, the addition of CO2 to the tetrameric bis-oxo intermediate leads to the formation of a tetrameric bis-carbonate samarium triflate. Thus, the concomitant reaction of CO2 with traces of O2 leads to the same bis-carbonate tetrameric assembly.

A simple and efficient method for multicomponant synthesis of 3,4-dihydropyrimidinones has been reported. All the reactions were carried out using samarium triflate as catalyst (10 mol%) at acetonitrile reflux. This procedure is applicable to a variety of substrates such as aliphatic, aromatic, and heterocyclic aldehydes.

Three-component coupling reactions of aldehydes, amines, and cyclic enol ethers have been carried out in the presence of samarium triflate to afford the corresponding pyrano and furanoquinolines in excellent yields with high endo-selectivity. The reaction conditions are mild and amenable to scale-up.

A versatile and efficient halogen-promoted highly regio- and stereoselective Friedel-Crafts (F-C) alkylation with alkenes has been developed with use of easily available and inexpensive NBS or I2 as the efficient halogen sources. Lewis acids, in particular metal triflates, are found to be effective catalysts for this halogen-promoted F-C alkylation. Among these, Sm(OTf)3 was the best catalyst. Electron-rich arenes smoothly underwent F-C alkylation with a variety of alkenes including alpha,beta-unsaturated carbonyl compounds.

Water-tolerant samarium triflate is found to be a suitable catalyst for the condensation of o-aminophenols and o-aminothiophenols with various aldehydes in aqueous ethanol.

A simple and efficient method for multicomponant synthesis of 3,4-dihydropyrimidinones has been reported. All the reactions were carried out using samarium triflate as catalyst (10 mol%) at acetonitrile reflux. This procedure is applicable to a variety of substrates such as aliphatic, aromatic, and heterocyclic aldehydes.

The presented synthesis proceeds under mild reaction conditions and includes an easy work-up.

In this communication we show that the instability of samarium diiodide (SmI(2)) in acetonitrile is a consequence of ionization of the reductant in this solvent. Samarium triflate (Sm(OTf)(2)) is exceptionally stable in acetonitrile for periods over six months and can be used with appropriate additives to initiate a ketyl-olefin coupling reaction in high yield.

Title compounds are produced in excellent yield and high endo-selectivity in a three-component coupling reaction between aldehydes, anilines and cyclic enol ethers.

Treatment of N-acyloxazolidinones with hydroxylamines using samarium triflate as a Lewis acid provides the corresponding hydroxamic acids in 50-98% yields at room temperature. The conversion proceeds with high degree of chemoselectivity and without racemization of chiral centers alpha- to the acyl group. [reaction: see text]

The cover picture shows the sonochemical preparation of samarium diiodide, samarium dibromide, and samarium triflate. The use of high intensity ultrasound (20 kHz) provides a straightforward and rapid approach to the synthesis of SmII compounds, some of which are not accessible by other means. Of particular importance is the fact that this approach can be used to produce SmII-based reductants in a wide range of solvents, including alcohols. Details are discussed in the Short Communication by R. A. Flowers II et al. on p. 5015 ff. R. A. F. gratefully acknowledges the National Science Foundation (CHE-0413845) for support of this work. Mr. Brian Casey is thanked for his assistance in the preparation of the cover.