19041-33-9Relevant articles and documents
Diastereoselective 'contra-Michael' addition of (-)- sparteine/organolithium complexes to secondary chiral cinnamyl amides
Bremand, Nathalie,Marek, Ilan,Normant, Jean F.
, p. 3383 - 3386 (1999)
'Contra-Michael' addition of (-)sparteine/organolithium reagents complexes to cinnamyl secondary amides derived from (R) or (S)-α- Methylbenzylamine occurs with matched or mismatched pairs, and allows an enantioselective access to 2-benzyl-amides,- acids,
Structural requirements for substrate in highly enantioselective hydrogenation over the cinchonidine-modified Pd/C
Sugimura, Takashi,Uchida, Takayuki,Watanabe, Junya,Kubota, Takeshi,Okamoto, Yasuaki,Misaki, Tomonori,Okuyama, Tadashi
experimental part, p. 57 - 64 (2009/06/17)
Relationship between substrate structure and enantioselectivity is studied for the asymmetric hydrogenation of 42 different (E)-α, β-disubstituted acrylic acids (propenoic acids) over cinchonidine-modified Pd/C. The β-phenyl group is indispensable for high enantioselectivity of α-phenylcinnamic acid (2,3-diphenylpropenoic acid, 81% ee), and substitution on this group affects markedly the selectivity. The high ee up to 92% was achieved by the β - p-alkoxyphenyl substitution, and the selectivity is ascribed mainly to stronger interaction of the substrate with the chiral modifier on the catalyst surface. In contrast, substitution on the α-phenyl group does not affect notably the enantioselectivity (80-82% ee) or even the α-phenyl group itself is not indispensable but replaceable with a properly bulky group for the high enantioselectivity.
An easy access to enantio-enriched α-substituted aldehydes by carbolithiation of β-phenyl or β-silyl-α,β-ethylenic aldehydes, protected with the monolithioamide of a chiral diamine
Brémand, Nathalie,Mangeney, Pierre,Normant, Jean F.
, p. 1883 - 1885 (2007/10/03)
Lithium amide derived from N,N,N′-trimethyl-1,2-diphenylethanediamine converts cinnamaldehyde to a lithium alkoxyamide which undergoes a regio- and stereoselective carbolithiation upon addition of various organolithiums. Subsequent hydrolysis or trapping with MeI delivers α-mono-, or α,β-disubstituted 3-phenylpropanals with e.e.s of 76-96%. Extension to a silylated α-enal is possible.