A highly stereocontrolled synthesis of (S-(-)-3-(4-tert-butyl)phenyl-1-N-(cis-2,6-dimethyl)morpholinyl-2-methylpropane via assymetric mannich reaction

✍ Scribed by Vladimir Vinković; Vitomir Šunjić

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 657 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(96)01011-3

✦ Synopsis

A b&act: By employing ris-2.6-dimethylmorpboljnemethylene immonium tetmchloroaluminate (5) enamines 9 and 10, prepared from 4-tt-rt-butylpropiophenone and propiophenone with (R)-(-j2-(methoxymethyl)pyrrolidine (8). were converted to chiral Man&h bases Il.12 with nearly 100% ce; optical purity of these &amino ketones drops significantly during isolation. Two-step reduction of the keto group in 11.12 afforded ~~J-(-~3-(~rerr-Bu~l)phenyl-1-N~ris-2,~ethyl)morpholinyl-2-methylpr ( 1). (Smantiomer of racemic systemic fungicide, generic. name fenpropimorph, and its congener 13 with 95.1% and 90.7% ce, respectively. A mechanistic model for asymmetric induction in the diastereoselective step is proposed.