The synthesis of the cyclic, naturally occurring amino acid baikiain from glycine and cis-1,4-butenediol is reported. The key step of the synthesis is an enantioselective phase transfer catalyzed allylation of the benzophenone imine of glycine t-butyl ester, catalyzed by a cinchonidine quaternary ammonium salt, which provided the allylated glycine in 82% yield and 80% e.e. Further deprotection and hydrolysis of the Schiff base followed by an intramolecular Mitsunobu ring closure reaction yielded the corresponding piperidine ring system in 77% yield, which by hydrolysis yielded baikiain hydrochloride in 36% overall yield. Hydrogenation of the double bond could provide access to (S)pipecolic acid, which is also an important chiral synthon.
Theoretical calculations were performed on 2, 5-aromatic substituted pyrroles which have a nitro-benzene or a cyano-benzene link to the nitrogen atom of the pyrrol fragment. The molecules manifested interesting semiconductor behavior that was confirmed when thin films were prepared and their corresponding electrical characterization undertaken. The reason for this behavior is discussed, with reference to the electron withdrawing feature of the substituents in the benzene chain.
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