This paper describes a novel strategy for the synthesis of 2,3,4-trisubstituted pyridines via organocatalyzed three-component reactions. A variety of pyridine derivatives are synthesized from readily available ketones with α,β-unsaturated aldehydes and ammonium acetate under a mild organocatalyst. This protocol leads to rapid N-annulation through C-C and C-N bond formation in a single operation...

1,3-Dienes derived from steroidal D-ring C 17-ketones undergo Ni(II)-catalyzed hydrovinylation to give 1,2- or 1,4-addition of ethylene. Using finely tuned phosphoramidite ligands, it is possible to synthesize either the C 20 ( R)- or ( S)-derivatives without mutual contamination. The proportion of the 1,4-adduct, which is also formed stereoselectively, can be minimized by optimizing the reacti...

The synthesis of α-amino carbonyl/carboxyl compounds is a contemporary challenge in organic synthesis. Herein, we present a stereoselective α-amination of amides employing simple azides that proceeds under mild conditions with release of nitrogen gas. The amide is used as the limiting reagent, and through simple variation of the azide pattern, various differently substituted aminated products c...

P.sub.2][O.sub.5]/[H.sub.3]P[O.sub.4] (PPA) was found to be an efficient new reagent for probing the mechanism of acylation reactions and Fries rearrangement of acyloxy benzene derivatives and also the direct acylation reactions of phenol derivatives with Carboxylic acids. The reactions proceeded smoothly in the presence of PPA and are highly selective for the preparation of the ortho isomers o...

BACKGROUND 1,1-Difluoroalkenes cannot only be used as valuable precursors for organic synthesis, but also act as bioisosteres for enzyme inhibitors. Among various methods for their preparation, the carbonyl olefination with difluoromethylene phosphonium ylide represents one of the most straightforward methods. RESULTS The combination of (chlorodifluoromethyl)trimethylsilane (TMSCF2Cl) and tri...

From the standpoint of enzymatic organic synthesis, NADH oxidase (NOX) will be a key enzyme that plays an essential role in the cofactor regeneration of NAD+ dependent enzymatic reactions. For example, enzymatic enantioselective oxidations of racemic secondary alcohols (Geueke et al., 2003; Riebel et al., 2003; Hummel & Riebel, 1996) and amino acids (Hummel et al., 2003a) have been reported as ...

A new flexible approach for the stereoselective synthesis of substituted 1H-pyrrol-2(5H)-ones and 3,6-dihydro-1H-pyridin-2-ones has been developed. The general strategy employed the stereoselective reduction of a series of α,β-unsaturated ketones under chelation control to give the corresponding allylic alcohols. Overman rearrangement to install the key C-N bond followed by conversion to either...

Introduction Metal complexes play an essential role in agriculture, pharmaceutical and industrial chemistry. Ligand, a metal surrounded by a cluster of ions or molecule, is used for preparation of complex compounds named as Schiff bases, which are condensation products of primary amines and aldehydes or ketones (RCH=NR′, where R & R′ represents alkyl and / or aryl substituents). This paper revi...

This account focuses on the application of ω-transaminases, lyases, and oxidases for the preparation of amines considering mainly work from our own lab. Examples are given to access α-chiral primary amines from the corresponding ketones as well as terminal amines from primary alcohols via a two-step biocascade. 2,6-Disubstituted piperidines, as examples for secondary amines, are prepared by bio...