Tandem crystallization strategies for resolution of 3,3,3‐trifluorolactic acid [CF 3 CH(OH)COOH] by chiral benzylamines | Zendy

Wong Lawrence W.Y. | Zendy; Vashchenko Elena V. | Zendy; Zhao Ying | Zendy; Sung Herman H.Y. | Zendy; Vashchenko Valerii V. | Zendy; Mikhailenko Vadim | Zendy; Krivoshey Alexander I. | Zendy; Williams Ian D. | Zendy

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Tandem crystallization strategies for resolution of 3,3,3‐trifluorolactic acid [CF 3 CH(OH)COOH] by chiral benzylamines

Author(s) -

Wong Lawrence W.Y.,

Vashchenko Elena V.,

Zhao Ying,

Sung Herman H.Y.,

Vashchenko Valerii V.,

Mikhailenko Vadim,

Krivoshey Alexander I.,

Williams Ian D.

Publication year - 2019

Publication title -

chirality

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.43

H-Index - 77

eISSN - 1520-636X

pISSN - 0899-0042

DOI - 10.1002/chir.23127

Subject(s) - chemistry , diastereomer , yield (engineering) , monoclinic crystal system , orthorhombic crystal system , enantiomer , coprecipitation , enantiomeric excess , crystallization , medicinal chemistry , chiral resolution , resolution (logic) , stereochemistry , crystallography , inorganic chemistry , crystal structure , organic chemistry , catalysis , enantioselective synthesis , materials science , artificial intelligence , computer science , metallurgy

Resolution of rac ‐3,3,3‐trifluorolactic acid by diastereomeric salt formation was reinvestigated. The use of (S)‐1‐phenylethylamine gives coprecipitation of two diastereomeric phases, 1 (S)‐[NH 3 CH(CH 3 )Ph](S)‐[CF 3 CH(OH)COO] and 2 (S)‐[NH 3 CH(CH 3 )Ph](R)‐[CF 3 CH(OH)COO]·H 2 O. Pure phase 1 may be obtained using molecular sieves as desiccants. Resolution by (S,S)‐2‐amino‐1‐phenylpropan‐1,3‐diol gives monoclinic (S,S)‐[NH 3 CH(CH 2 OH)CHOHPh] (R)‐[CF 3 CH(OH)‐COO] 3 with minor (S)‐3,3,3‐trifluorolactate contamination, which is precluded in the recrystallized orthorhombic form 4 . A new resolution using inexpensive phenylglycinol gives pure phase 5 (S)‐[NH 3 CH(CH 2 OH)Ph] (S)‐[CF 3 CH(OH)COO] in 76% yield, 94% ee in a single step, in preference to its (S)‐(R) diastereomer 6 . Overall efficient resolution for both enantiomers of the trifluorolactic acid (each ca. 70% yield, 99% ee) may be achieved by various two‐step “tandem” crystallizations, involving direct addition of either water or a second base to the filtrate from the initial reaction.

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