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Preparation and use of chloromethyl (−)‐menthyl ether in the synthesis of optically pure α‐branched α‐amino nitriles
Author(s) -
Shatzmiller Shimon,
Dolithzky BenZion,
Bahar Eliezer
Publication year - 1991
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.199119910165
Subject(s) - chemistry , diastereomer , hydrolysis , acetal , ether , cleavage (geology) , silica gel , optically active , organic chemistry , silyl ether , column chromatography , silylation , catalysis , geotechnical engineering , fracture (geology) , engineering
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 mixtures of diastereomers are separated into the pure components 7a, 7b and 8a, 8b by simple silica gel column chromatography. Hydrolysis of these products (H 2 O 2 /Na 2 CO 3 , ultrasound) followed by NO 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.