Sebastian Hirner

Cruise Media GmbH

The first synthesis of N-tosyl imines from various cyclopent-2-enones and cyclohex-2-enones was achieved by direct condensation with tosyl amide in the presence of TiCl(OEt)(3) and Et3N. In addition, N-tert-butylsulfonyl imines from five- to seven-membered cycloalk-2-enones were obtained through formation of the respective oximes and subsequent Hud...

Rhodium(I)/Binap complexes catalyze highly enantioselective additions of methyl- and arylaluminum reagents to cyclic α,β-unsaturated N-tosyl ketimines. Depending on the solvent and substituents at the ring, the reaction occurs either in a 1,2-manner to deliver α-tertiary allylic amines or in a 1,4-manner to yield, after subsequent reduction, 3-subs...

The feasibility of kinetic resolutions of racemic monosubstituted cyclohex-2-enones by Rh/binap-catalyzed reactions was investigated. 1,2-Addition of AlMe(3) to the 5-substituted derivatives furnished allylic alcohols in the matched case, while the less reactive enantiomers were either left over or transformed into trans-3,5-disubstituted cyclohexa...

An easy and straightforward synthesis of alpha-amino amides via a base-mediated rearrangement of modified Weinreb amides into N,O-acetals is presented. Subsequent arylation, alkylation, alkenylation, or alkynylation of this intermediate affords the corresponding alpha-amino amides in excellent yields. Furthermore, a more generalized protocol for th...

Total synthesis of the anticancer 1,4-dioxane containing natural products silvestrol (1) and episilvestrol (2) is described by an approach based on the proposed biosynthesis of these novel compounds. The key steps included an oxidative rearrangement of the protected d-glucose derivative 11 to afford the 1,4-dioxane 12, which could be elaborated to...

An efficient and diastereoselective synthesis of α-amino acids from readily available starting materials has been developed. The key feature of this reaction is an umpolung of a glycine-derived enolate, providing an alternative approach for the synthesis of α-amino acids.

An efficient and diastereoselective synthesis of α-amino acids from readily available starting materials has been developed. The key feature of this reaction is an umpolung of a glycine- derived enolate, providing an alternative approach for the synthesis of α-amino acids.

Wenige Beispiele für die Umpolung von Enolaten sind bekannt, doch ein solcher Prozess liegt der Titelreaktion zugrunde: Aus einem Weinreb-Amid wird durch Umsetzung mit einer Base zunächst ein Iminiumion gebildet, an das anschließend ein Grignard-Reagens addieren kann (siehe Schema). Chirale Amide führten zu hoch diastereoselektiven nucleophilen Add...

(Chemical Equation Presented) A rare example of the umpolung of an enolate forms the basis of the title reaction. In this procedure, a Grignard reagent is added to the iminium ion formed from the Weinreb amide upon treatment with a base (see scheme). When a chiral amide was used as the starting material, the nucleophilic addition proceeded with hig...

An efficient microwave-assisted rearrangement of activated vinylaziridines to 3-pyrrolines is described. The rearrangement proceeds in good to excellent yields and is mediated by NaI or LiI in MeCN at elevated temperatures. The synthetic utility of this reaction is shown in an efficient formal total synthesis of the antibiotic (-)-anisomycin.

Methyltrioxorhenium (MTO) catalyses the olefination of ketones with ethyl diazoacetate in the presence of triphenylphosphane. Unactivated ketones require the addition of 0.5equiv of benzoic acid to achieve good yields, while trifluoromethyl ketones require no co-catalyst. The optimised system allows the olefination of aromatic, aliphatic, unsaturat...