Ion-molecule reactions catalyzed by a single gold atom

We report that Au atoms within van der Waals complexes serve as catalysts for the first time. This was observed in ionization-induced chemistry of 1,6-hexanediol–Au and 1,8-octanediol–Au complexes formed in superfluid helium nanodroplets, where the addition of Au atom(s) made C₂H₄⁺ the sole prominent product in dissociative reactions. Density functional theory (DFT) calculations showed that the Au atom significantly strengthens all of the C–C bonds and weakens the C–O bonds in the meantime, making the C–C bonds stronger than the two C–O bonds in the ionized complexes. This leads to a preferential cleavage of the C–O bonds and thus a strong catalytic effect of the Au atoms in the reactions.

Single Au atoms within van der Waals complexes are found to serve as catalysts in ionisation-induced chemistry for the first time.     

ALKYLATIOIM,ACYLATION, AND ARYLATION PRODUCTS OF 1-CYANO-ISOTHIOCHROMANE

Abstract

1-Cyano-isothiochromane (1a) can be alkylated in position 1, using the carbanion that is formed from sodium amide, sodium hydride, or n-butyllithium. With methyl iodide or ethyl iodide 1c and 1d are formed; with α-halogenated ether or thioether, 1e and 1f; with propargyl bromide, 1h; with bromo acetophenone, li; and with ethyl chloroacetate, 1k. Similarly, acylation with benzoyl chloride leads to 11, and with 2,4-dinitrofluorobenzene to 1m. The alkylation products of 1a can be oxidized with peracids to the sulfones 2 and with LiAlH₄ reduced to 1-aminomethyl-isothiochroman (3): Acid hydrolysis of 1 gave isothiochromane-1-carboxylic acids, 4, whereas when 1 is treated with hydrogen peroxide in alkaline medium the S-dioxide and the S-oxide acid amides, 5 and 6 respectively, are formed.