Über eine Racemat‐Spaltung des DL‐Allothreonins

Abstract

Die diastereomeren Brucinsalze des L‐ und D‐N‐Phthaloyl‐allothreonins zeigen ausgeprägte Löslichkeitsunterschiede in Äthylenglykol‐monomethyläther (Methylcellosolve). Dies ermöglicht eine einfache Trennung des DL‐Allothreonins in die optischen Antipoden.

Preparation of Optically Active Allothreonine via Optical Resolution by Replacing Crystallization.

“…Therefore, synthetic DLaThr 2-4) has been subjected to optical resolution by separating the diastereoisomeric salts of DL-aThr derivatives to obtain the enantiomers. 5,6) In our previous paper, 7) DL-aThr was found to exist as a conglomerate and to be optically resolved by preferential crystallization and replacing crystallization of DL-aThr. The optical resolution by replacing crystallization is a procedure for obtaining an enantiomer from a conglomerate, and is achieved by allowing an optically active co-solute to coexist in a racemic supersaturated solution.…”

Preparation of Optically Active Allothreonine by Separating from a Diastereoisomeric Mixture with Threonine

“…In addition, D-and L-aThr serve as useful chiral building blocks in asymmetric syntheses. 4) D-and L-aThr have been obtained by an asymmetric synthesis, 5) optical resolution of DL-aThr, [6][7][8] enzymatic resolution of N-acylated and O-methylated 9) and selective enzymatic hydrolysis of a mixture of N-acetylated and O-benzylated L-Thr and D-aThr. 10) Of these methods, optical resolution by separating the diastereoisomers by crystallization seemed to be a simple and efficient procedure.…”

“…10) Of these methods, optical resolution by separating the diastereoisomers by crystallization seemed to be a simple and efficient procedure. However, such optical resolution would require an optically active compound such as a resolving agent in separating the diastereoisomeric salts, 6) seed crystals in preferential crystallization, 7) and an optically active cosolute in replacing crystallization. 8) We have already reported the preparation of aThr by replacing crystallization with alanine as a cosolute.…”