Asymmetric Michael addition of a recyclable chiral amine: inversion of stereoselectivity caused by the difference of ethereal solvents.
The Michael addition of a chiral amine [(-)- 6] to alpha,beta-unsaturated esters ( 4) was attained and the stereoselectivity was inverted by changing the solvent from diethyl ether to tetrahydrofuran when alpha,beta-unsaturated esters having an aromatic ring at the beta-position were employed. In addition, the chiral auxiliary in the Michael adducts ( 9A) was facilely removed with N-iodosuccinimide to afford beta-amino esters ( 10A) and 2-methoxy- d-bornylaldehyde ( 11), which can be reclaimed to the chiral amine ( 6) by reductive amination.
Department of Pharmaceutical Manufacturing Chemistry, 21st COE program, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan. node@mb.kyoto-phu.ac.jp
Manabu
M
Node
Daisuke
D
Hashimoto
Takahiro
T
Katoh
Shunsuke
S
Ochi
Minoru
M
Ozeki
Tsunefumi
T
Watanabe
Tetsuya
T
Kajimoto
D000588:Amines / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D015394:Molecular Structure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013237:Stereoisomerism; D013447:Sulfites / Q000737:chemistry
D000588:Amines; D004987:Ethers; D000644:Quaternary Ammonium Compounds; D012997:Solvents; D013447:Sulfites; C042345:hydrogen sulfite