- An efficient, asymmetric synthesis of pipecolic acid and 2-alkyl pipecolic acids
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Both (R)- and (S)-pipecolic acids and their 2-alkyl derivatives have been synthesized via diastereoselective alkylations of (R)-5-phenylmorpholin-2-one 5.
- Hou, Duen-Ren,Hung, Shin-Yi,Hu, Chung-Cheng
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p. 3858 - 3864
(2007/10/03)
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- Preparation and Use of Chloromethyl (-)-Menthyl Ether in the Synthesis of Optically Pure α-Branched α-Amino Nitriles
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The synthesis of optically pure chloromethyl (-)-menthyl ether (2b) and its use in the synthesis of di-(-)-menthyl acetal (-)-menthyl (+)-menthyl acetals are described.The diastereomeric mixed acetals 7a,b and 8a,b are easily obtainable from the nitrones 5 and 6, KCN and 2b.The mixture of diastereomers are separated into the pure components 7a, 7b and 8a, 8b by simple silica gel column chromatography.Hydrolysis of these products (H2O2/Na2CO3, ultrasound) followed by N-O cleavage affords the heterocyclic α-methyl-α-amino amides 11a, 11b and 12a, 12b.These are subsequently hydrolyzed to give the corresponding α-methyl-α-amino acids with S and R configuration, respectively.
- Shatzmiller, Shimon,Dolithzky, Ben-Zion,Bahar, Eliezer
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p. 375 - 379
(2007/10/02)
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