Evidence for an interphase deprotonation of Pd(II)-amine complexes with weak carbonate base has been gained for the first time. When a rate-limiting deprotonation step is involved in the catalytic cycle, controlling the structure (shape and size of the particles) and/or molar excess of the carbonate base used can significantly increase the reaction rate of Buchwald-Hartwig aminations. By taking such a "base effect" into account a general protocol for the intermolecular amination of aryl iodides with all types of amines has been developed based on a standard Pd-BINAP catalyst, using cesium carbonate as the base.

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The diastereoisomeric 2-methyltetrols, 2-methylthreitol and 2-methylerythritol, were recently reported as major secondary aerosol components in natural forest aerosols and proposed as molecular markers for the photooxidation of isoprene. In this study, we examine the complex electron and methane chemical ionization behaviors of their trimethylsilyl ethers. In order to gain insight into their fragmentation behaviors, threitol and erythritol were studied as model compounds, and deuterium labeling of the trimethylsilyl groups and ion trap MS2 experiments were performed.

A new strategy for the synthesis of the title compounds via a regio- and chemoselective one-pot inter- and intramolecular Buchwald-Hartwig amination of 2-chloro-3-iodopyridine with aminoazines and -diazines is reported.

[reaction: see text] The synthesis of dipyrido[1,2-a:2',3'-d]imidazole and hitherto unknown benzo and aza analogues is described. These relatively complex polycyclic heterocycles could be smoothly prepared in one step from commercially available building blocks. Mechanistically, the developed procedure involves orthogonal (Pd and Cu catalyst) or auto-tandem (Pd catalyst) catalysis via regioselective inter- and intramolecular C-N bond formation.

Fast palladium-catalyzed aminations of activated and unactivated azaheteroaryl chlorides as well as unactivated aryl chlorides have been achieved using temperature-controlled microwave heating. Good yields (75-91%) were obtained in a reaction time of only 10 minutes.

D-Ring substituted 11H-indoloA C H T U N G T R E N N U N G [3,2-c]quinolines (4) have been prepared via auto-tandem consecutive intermolecular Buchwald-Hartwig reaction and intramolecular palladium-catalyzed arylation on 4-chloroquinoline (1) with N-unsubstituted 2-chloroanilines (2). The reported 11H-indoloA C H T U N G T R E N N U N G [3,2-c]quinolines (4) represent the first examples in which tandem catalysis has been used to construct N-unsubstituted carbolines.Keywords: amination; C À H activation; malaria; palladium; tandem catalysis IntroductionIn 2003 our research group published a communication which described a new method for the synthesis of 11H-indoloA C H T U N G T R E N N U N G [3,2-c]quinoline (4a) starting from commercially available 4-chloroquinoline (1) and 2-chloroA C H T U N G T R E N N U N G aniline (2a) (Scheme 1).[1] The methodology consists of two consecutive palladium-catalyzed reactions: a selective Buchwald-Hartwig reaction (chemoselective oxidative addition) followed by an intramolecular arylation involving C À H activation. [2,3] The latter reaction is interesting in itself as published examples on intramolecular Pd-catalyzed arylations of electron-deficient heteroaromatics are scarce in comparison with electron-rich heteroarenes.[3c] Selective N-5 methylation of the obtained 11H-indoloA C H T U N G T R E N N U N G [3,2-c]quinoline (4a) yielded the antiplasmodial natural product isocryptolepine (5-methyl-5H-indoloA C H T U N G T R E N N U N G [3,2-c]quinoline) (5a) (Scheme 1).[4] The increasing resistance of parasites of the genus Plasmodium to well known drugs like chloroquine and mefloquine prompted us to investigate more closely the biological Scheme 1. Synthesis of 4a via consecutive palladium-catalyzed reactions.

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