RESUMO
The non-Kolbe reaction of N-benzoyloxazolidine derivatives 6 derived from L-serine gave optically active N,O-acetals 7 when graphite was used as an anode material. This reaction represents the first example of "memory of chirality" in carbenium ion chemistry. The material used for the anode was critical for the memory of chirality. The substitution of carboxyl group with methoxyl group was found to proceed with an inversion mechanism.
RESUMO
A new facile method for monoacylation of diols has been developed. A variety of cyclic and acyclic diols, in particular 1,2-diols, were selectively monobenzoylated in good yields by the reaction with benzoyl chloride in the presence of a catalytic amount of dimethyltin dichloride and inorganic bases such as potassium carbonate. Furthermore, the method was successfully applied to a kinetic resolution of racemic 1-phenyl-1,2-ethanediol using a chiral organotin catalyst. The ee was dependent on the kind of base, water as an additive, and the reaction temperature.
Assuntos
Carbamatos/síntese química , Fluoretos/síntese química , Ureia/análogos & derivados , Ureia/síntese química , Aminas/química , Aminas/metabolismo , Carbamatos/química , Carbamatos/metabolismo , Eletroquímica , Fluoretos/química , Fluoretos/metabolismo , Ésteres do Ácido Fórmico/química , Ésteres do Ácido Fórmico/metabolismo , Espectroscopia de Ressonância Magnética , Ureia/química , Ureia/metabolismoRESUMO
[formula: see text] This report describes a new method to prepare optically active methylphenidate starting from piperidine. The method consists of a transformation of N-methoxycarbonylpiperidine to the corresponding alpha-methoxylated carbamate I by utilizing electrochemical oxidation followed by the coupling reaction with optically active Evans imides II to produce optically active methylphenidate derivatives III with high stereoselectivities, threo-(2R,2'R)-Methylphenidate (IV; Ar = Ph; Ritalin) was easily prepared from III in three steps.