Enantioselective synthesis via the nucleophilic alkylation of hydrazones: Acetals as chiral auxiliaries.

✍ Scribed by Mohamadou Thiam; Francine Chastrette

• Publisher: Elsevier Science
• Year: 1990
• Tongue: French
• Weight: 231 KB
• Volume: 31
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)88824-3

✦ Synopsis

Oiastereoselective addition of organolithium reagents on hydrazones vicinal to chiral cyclic acetals provide chiral hydrazinoacetals from which optically active aminoacetals and aminoacids can be prepared. Recently the syntheses of optically active amines involving the addition of organometallic reagents on chiral hydrazones of aldehydes as the key step have appeared in the literature (l-5). Good diastereo and enantioselectivities were observed when hydrazones obtained from chiral N-aminoephedrine or proline-derived hydrazines were reacted respectively with either Grignard (1) or organolithium (2) and organocerium (3,4) reagents. In the third ; 60.5 (CH3) ; 59.3 (CH3) ; 55.4 (CH3) ; 55.0 (CH) ; 48.1 (CH3) ; 15. : 102.1 (CH) ; 98.4 (CH) ; 82.0 (CH) ; 81.7 (CH) ; 79.9 (CH) ; 59.3 (CH3) ; 55.0 (CH3) ; 68.0 (CH3) ; 28.8 (CH2) 4.5 (d, J = 6Hz, 1H) ; 4.1 -3.5 (m, 5H) ; 3.3 (S (d, J = 8Hz, 1H). 13C nmr : 104.0 (CH) ; 75.5 (CH2) 28.0 (Ch2) ; 18.0 (CH3).