Asymmetric Induction at C(?) and C(?) ofN-Enoylsultams by Organomagnesium 1,4-Addition/Enolate Trapping
作者:Wolfgang Oppolzer、Giovanni Poli、Arend J. Kingma、Christian Starkemann、G�rald Bernardinelli
DOI:10.1002/hlca.19870700825
日期:1987.12.16
The 1,4-addition of alkylmagnesium chlorides to conjugated N-enoylsultams and subsequent ‘enolate trapping’ with aq. NH4Cl or MeI/hexamethylphosphoric triamide generated centers of asymmetry at C(β) and/or at C(α) with good to excellent π-face defferentiation as demonstrated by the conversions 12, 14, and 89. This holds also for the regioselective 1,4-addition of EtMgC1 to a dienoylsultam (1516). Reactive
A FACILE ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED ALKANOIC ACID THE HIGHLY STEREOSELECTIVE MICHAEL ADDITION OF GRIGNARD REAGENTS TO α,β-UNSATURATED CARBOXYLIC AMIDES DERIVED FROM L-EPHEDRINE
作者:Teruaki Mukaiyama、Nobuharu Iwasawa
DOI:10.1246/cl.1981.913
日期:1981.7.5
The Michael addition of Grignard reagents to chiral α,β-unsaturated carboxylic amides derivedfrom 1-ephedrine affords highly optically active β-substituted alkanoic acids after acid hydrolysis. This high stereoselectivity is explained by considering the formation of rigid internal chelate complexes.
Asymmetric conjugate addition reaction by the use of ()-γ-trityloxymethyl-γ-butyrolactam as a chiral auxiliary
作者:Kiyoshi Tomioka、Toshiro Suenaga、Kenji Koga
DOI:10.1016/s0040-4039(00)84021-6
日期:1986.1
(S)-γ-Trityloxymethyl-γ-butyrolactam (2) serves as a chiralauxiliary in the conjugate addition reaction of the corresponding imide (3) of α,β-unsaturated carboxylic acids with Grignard reagents in the presence of CuBrSMe2 in THF to give, after hydrolysis, the β,β-disubstituted carboxylic acids (5) with predictable absolute configuration and high enantiomeric excess.
Enantioselective Carbometalation of Cinnamyl Derivatives: New Access to Chiral Disubstituted Cyclopropanes— Configurational Stability of Benzylic Organozinc Halides
作者:Stephanie Norsikian、Ilan Marek、Sophie Klein、Jean F. Poisson、Jean F. Normant
Highly stereoselective addition of organolithium reagents to chiral oxazolines. Asymmetric synthesis of 3-substituted alkanoic acids and 3-substituted lactones