A Practical Synthesis of Chiral Oxazolines through a Highly Diastereoselective Coupling–Cyclization Reaction of N‐(Buta‐2,3‐dienyl)amides and Aryl Iodides

Abstract

A highly trans diastereoselective synthesis of 2,4,5‐trisubstituted oxazoline derivatives is described that proceeds through a palladium‐catalyzed coupling–cyclization reaction of N‐(buta‐2,3‐dienyl)amides with aromatic iodides. The reaction with optically active substrates provides convenient access to highly enantioenriched oxazoline derivatives with excellent 1,2‐induction.

Process for (S)-Ketamine and (S)-Norketamine via Resolution Combined with Racemization

“…In view of the similarity of the structure of 3 with that of ketamine and norketamine, our initial idea was that norketamine could be obtained by direct amination via Ritter reaction under acidic conditions. The Ritter amination of intermediate 3 was conducted under the general conditions of H 2 SO 4 /ACN 28 followed by acid hydrolysis at 90 °C for 24 h to norketamine. However, what puzzled us was that the obtained compound was not norketamine but its isomer 10 which was confirmed by NMR spectra (in the Supporting Information).…”

Diastereoselective Synthesis of N-Protected 2,3-Dihydropyrroles via Iron-Catalyzed Cycloisomerization of α-Allenic Sulfonamides

“…The nonprotected primary α-allenic amines are difficult to prepare and they exhibit poor stability. However, the corresponding N -mesylated derivative 5a , which is quite stable, was readily prepared from the mesylated propargylic amine and paraformaldehyde . Initial attempts to obtain a cyclization of N -mesylated 5a using DCM, 5 mol % of Fe catalyst 1 and 5 mol % of TMANO at room temperature were unsuccessful (Table , entry 1).…”

“…However, the corresponding N-mesylated derivative 5a, which is quite stable, was readily prepared from the mesylated propargylic amine and paraformaldehyde. 14 Initial attempts to obtain a cyclization of N-mesylated 5a using DCM, 5 mol % of Fe catalyst 1 and 5 mol % of TMANO at room temperature were unsuccessful ( Interestingly, with an increased catalyst loading, the reaction could also be made to work in water with a modest yield of 36% (Table 1, entry 9). Comparative yields were obtained without the addition of K 2 CO 3 , but the reaction proved to be more reproducible in its presence.…”