New general method for regio- and stereoselective allylic substitution with aryl and alkenyl coppers derived from Grignard reagents.
Allylic substitution with sp(2)-carbon reagents (aryl and alkenyl anions) was realized by using allylic picolinates and copper reagents derived from RMgBr and CuBr x Me(2)S to afford anti S(N)2' products regio- and stereoselectively. Steric and electronic factors in the reagents and the size of the methylene substituents around the allylic moiety marginally affected the selectivity. The reaction system was compatible with alkyl reagents as well. Furthermore, the substitution was applied to construction of a quaternary center and synthesis of (-)-sesquichamaenol. Electron-withdrawing nature of the pyridyl group and chelation of the C(=O)-C(5)H(4)N to MgBr(2) generated in situ were found to be responsible for the high efficiency of the substitution.
Kiyotsuka
Yohei
Y
Department of Biomolecular Engineering, Tokyo Institute of Technology, Box B52, Nagatsuta-cho 4259, Midori-ku, Yokohama 226-8501, Japan.
Katayama
Yuji
Y
Acharya
Hukum P
HP
Hyodo
Tomonori
T
Kobayashi
Yuichi
Y
D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D000475:Alkenes; D000498:Allyl Compounds; D009942:Organometallic Compounds; D003300:Copper