20706-69-8Relevant articles and documents
Efficient resolution of menthylamine with inexpensive (r,r)-tartaric acid by dielectrically controlled resolution (DCR)
Schmitt, Magdalena,Schollmeyer, Dieter,Waldvogel, Siegfried R.
, p. 1007 - 1012 (2014/03/21)
A practical procedure for the resolution of menthylamine 2 with (R,R)-tartaric acid [(R,R)-3] as resolving agent is presented. Variation of the solvent system allows both enantiomers of 2 to be selectively crystallized. Performing the resolution in methanol containing 6 % water leads to (-)-2·(R,R)-3·MeOH. The other, less-soluble diastereomeric salt is obtained by applying a solvent system consisting of methanol with 19 % water with a yield of 14 %. Subsequent basic workup with aqueous sodium hydroxide gave the free menthylamine compounds. Further workup of the mother liquors and an additional recrystallization step allowed the (-)-2·(R,R)-3·MeOH salt to be obtained in an overall yield of 22 %; the other salt (+)-2·(R,R)-3·MeOH·H2O was obtained in 23 % yield. This is another important example of the dielectrically controlled resolution of an interesting amine by using inexpensive (R,R)-tartaric acid as resolving agent. With the same inexpensive resolving agent, (R,R)-tartaric acid, both antipodes of menthylamine can be selectively crystallized as diastereomeric salts. The concentration of water determines which salt is formed. In a few simple resolution steps, good yields and high enantiomeric excess can be achieved. Copyright
