90933-77-0Relevant academic research and scientific papers
Diastereoselective addition of chiral aliphatic imines and 2-alkyl-1,3-oxazolidines to organometallic reagents
Higashiyama,Fujikura,Takahashi
, p. 722 - 728 (2007/10/02)
The reaction of organocerium reagents with chiral aliphatic imines derived from (R)-O-methylphenylglycinol afforded the corresponding amines with high diastereoselectivity. In contrast, the reaction of Grignard reagents with chiral 2-alkyl-1,3-oxazolidines derived from (R)-N-methylphenylglycinol afforded the amines with changeover in diastereoselectivity.
Reversal of Diastereofacial Selectivity in the Addition Reaction of Organometallics to Chiral Imines
Ukaji, Yutaka,Watai, Toshiyuki,Sumi, Takashi,Fujisawa, Tamotsu
, p. 1555 - 1558 (2007/10/02)
It was observed that diastereofacial selectivity in the addition reaction of organometallics to the chiral imines derived from (R)-2-methoxy-1-phenylethylamine was regulated under appropriate conditions; i. e., organolithium and organocerium reagents added from the re-face of the chiral imines selectively, while organocopper reagents attacked from the si-face.The utility of the present method was demonstrated in the enantioselective synthesis of solenopsin A.
Enantioselective Synthesis of Primary Amines via Grignard Additions to Stereogenic N-(α-Phenyl-β-(benzyloxy)ethyl)nitrones
Chang, Zen-Yu,Coates, Robert M.
, p. 3475 - 3483 (2007/10/02)
Addition of a wide range of Grignard to C-aryl- and C-alkyl-N-(α-phenyl-β-(benzyloxy)ethyl)nitrones (4-7) occurred with high diastereoselectivity (90:10 to 97:3 ratios) and good yields (56 - 97percent).Notable exceptions are allyl- and (o-methoxyphenyl)magnesium bromides (low selectivity but satisfactory yields) and isopropyl- and tert-butylmagnesium chlorides (high selectivity but 33 - 34percent yields) with C-phenylnitrone 4.The relative stereochemistry of hydroxylamine adducts 8a,b (from reaction of 4 with CH3MgBr) and 19a,b (from C-pentylnitrone 7 with MeMgBr) was provenby various correlations and/or by degradation to enantiomerically enriched amines.The other stereochemical assignments are based upon 1H NMR spectral and polarity correlations and/or by analogy to the two proven cases.The configuration of the major product can be rationalized by assuming that the Grignard reagents attack the nitrone face opposite to the pseudoequatorial N-(α-phenyl) group in a six-membered magnesium chelate (27 -> 28). 1H NMR spectral evidence indicates that a 1:1 complex of nitrone 4 and magnesium bromide exists in a chelated structure (29B) in CD2Cl2.Enantioselective syntheses of (S)-α-phenylethylamine (94percent ee) and (S)-2-heptylamine (82percent ee) were accomplished in five steps (33-39percent overall yields) from optically pure (S)-nitrones 4 and 7.
Diastereoselective Synthesis of Chiral Secondary Amines with Two Chiral Centers Directly Attached to the Nitrogen Atom
Eleveld, M.B.,Hogeveen, H.,Schudde, E.P.
, p. 3635 - 3642 (2007/10/02)
The synthesis of the amines 1a-f by hydrogenation of the corresponding imines 4a-f occurs with a diastereoselectivity ranging from 33percent to higher than 90percent.The absolute configurations of 1b-f have been determined by either X-ray analysis (1b and
ENANTIOSELECTIVE REDUCTION OF ACETOPHENONE BY BORANE.CHIRAL AMINE COMPLEXES
Eleveld, M. B.,Hogeveen, H.
, p. 635 - 638 (2007/10/02)
The enantioselective reduction of acetophenone by the borane.chiral amine complexes BH3.1a - BH3.1d affords 1-phenyl-1-ethanol with o.y. up to 42percent.
ENANTIOSELECTIVE ADDITION OF N-BUTYLLITHIUM TO BENZALDEHYDE IN THE PRESENCE OF CHIRAL LITHIUM AMIDES
Eleveld, M. B.,Hogeveen, H.
, p. 5187 - 5190 (2007/10/02)
The reaction of n-butyllithium with benzaldehyde in the presence of chiral lithium amides 1a-e gives 1-phenyl-1-pentanol with optical yields up to 90 percent.
