66. Synthese und Reaktionen des 5--2,2-dimethyl-4-phenyl-3-oxazolins

Article abstract of DOI:10.1002/hlca.19850680309

Synthesis and Reactions of 5--2,2-dimethyl-4-phenyl-3-oxazoline.The title compound 8 has been synthesized in a one-pot reaction of 4'-(dimethylamino)benzoin (4) with 2-propanone and NH3.The preparation of the intermediate 4 from 3 is the first example of an acid-catalyzed transformation of the stable benzoin 3 into the corresponding less stable benzoin 4.Structures and yields of various by-products occuring under different reaction conditions during the synthesis of 8 from 4 are given.The O-atom of the 3-oxazoline ring in 8 could be replaced by S from P2S5 yielding the 3-thiazoline 14.Separation of the enantiomers of the racemate 8 could only be performed by transforming them into the trimethylanilinium salts 8b and 8c of (-)- and (+)-10-camphorsulfonic acid, respectively.Solid NaOAc in boiling toluene caused the precipitation of the 10-camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (-)-(5S)-8 and (+)-(5R)-8.Their absolute configurations are deduced from an X-ray analysis of 8b.