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Electrochemical reactions in electrospray may affect the electrospray ionization mass spectrometry (ESI-MS) detection of the analytes. During ESI-MS analysis of 2,3′-bisindolylmethanes in the positive-ion mode, when methanol or acetonitrile was used as the solvent, electrochemical oxidation products as the dehydro and radical cations were observed. Lower sample introduction rates tended to result in a higher oxidation ratio of 2,3′-bisindolylmethanes. The ESI-MS experiments of 2,3′-bisindolylmethanes in different acetonitrile/methanol solvent mixtures indicated that abundant H+, Na+ or K+ would facilitate the adduct formation process, and otherwise electrochemical oxidation dominated the ionization process. Additionally, when dichloromethane was used as the solvent, [M − 3H]+, [M − 2H]+˙ and [M − 3H + O]+ ions are the predominant ions, and the experimental results revealed that the dehydrogenation and oxidative dehydrogenation reactions of 2,3′-bisindolylmethanes in dichloromethane are electrochemical reactions.

Twelve 2,3′-bisindolylmethanes with various substituents were investigated using electrospray ionization quadrupole time-of-flight tandem mass spectrometry in positive ion mode. A retro-[3+2] reaction was observed in the collision-induced dissociation spectra of protonated 2,3′-bisindolylmethanes for the first time. The mechanism of retro-[3+2] reaction was concerted or stepwise. For the concerted pathway, carbon–carbon bonds of a protonated compound simultaneously cracked and the m/z 208 ion ([C15H10D2N]+) was observed with hydrogen–deuterium exchange labeling. The stepwise pathway goes through 1,3-hydrogen migration twice and the m/z 208 ion ([C15H10D2N]+) and m/z 207 ion ([C15H11DN]+) were detected with deuterium labeling. In the deuterium-labeled tandem mass spectrum for one compound, only the peak at m/z 208 was present at high abundance, suggesting that the concerted pathway is more likely. In addition, the substituents have no obvious trends on the ratios of the product intensity to the bas...

A series of 2,3′-bisindolylmethanes were analyzed using electrospray ionization quadrupole time-of-flight and radical ions ([M]+) and dehydro cations ([M−H]+) were detected in positive-ion mode. The formation pathways of [M]+ were proposed confirmed by D-labeling, free radical trapping and CID-MS/MS experiments. It was found that [M]+ ion was formed in droplets by the direct loss of an electron and the processes forming [M]+ and [M−H]+ ions were independent. The fragmentation pathways of the [M−H]+ and [M]+ ions were studied by CID-MS/MS. The dominant fragmentation pattern of [M]+ ions is the loss of benzyl radical comparing to that of [M−H]+ ions.

The enantioselective double Michael reaction of N-Boc-3-nonsubstitued oxindoles with dienones catalyzed by chiral monoimide protected cyclohexane-1,2-diamines was developed. A wide range of optically active spirocyclic oxindoles were obtained up to 98% yield and up to 89% ee.

Chiral bifunctional tertiary amine thiourea was applied to catalyze the asymmetric hydroxyamination of 3-subsituted oxindoles with nitrosobenzene to construct 3-amino-2-oxindoles with quaternary stereocenters in good yields (up to 91%) and enantioselectivities (up to 90% ee).

A new ellagitannin along with eight known compounds has been isolated from the ethanol extract of the fruit of Phyllanthus emblica L. The chemical structure of the new compound was established as Phyllanthunin (1) by HR-ESI-MS, 1D and 2D NMR spectroscopic analysis.

A simple method for the straightforward regioselective synthesis of 2,3-mannoepoxy-beta-cyclodextrin, which is a valuable precursor for further functionalization of beta-cyclodextrin, is achieved under aqueous conditions without any organic solvents at a moderate yield.

A convenient and economic method for the regioselective synthesis of mono-2-tosyl-β-cyclodextrin was achieved by using the combination of N-tosylimidazole and carbonate buffer in DMF, the reaction does not require strict anhydrous or specific basic catalysts.

The title reaction affords succinimide derivatives having adjacent tertiary and quaternary stereocenters.

A bifunctional piperidine—thiourea organocatalyst efficiently catalyzes the asymmetric hydroxyamination of oxindoles (I) with nitrosobenzene (II).

A highly diastereoselective and enantioselective Michael addition of α-substituted isocyanoacetates with maleimides catalyzed by bifunctional tertiary amine thioureas has been developed. Various chiral succinimide derivatives bearing adjacent quaternary and tertiary stereocenters were prepared in excellent yields (up to 98%), diastereoselectivities (up to 99:1), and enantioselectivities (up to 98% ee). The synthetic utility of chiral succinimide derivatives is also demonstrated in the preparation of h5-HT(1d) receptor agonist motifs.