Detail of "938-16-9"

Reference

Effects of the structure of optically active alkylaluminum compounds on the asymmetric reduction of alkyl phenyl ketones

Effects of the structure of optically active alkylaluminum compounds on the asymmetric reduction of alkyl phenyl ketones. Menicagli, R.; Caporusso, A. M.; Giacomelli, G. P.; Lardicci, L. (Cent. Stud. Macromol. Stereoordinate Otticamente Attive, CNR, Pisa, Italy). Chim. Ind. (Milan), 58(12), 876 (Italian) 1976. CODEN: CINMAB. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) The redn. of RCOPh (I; R = Et, Me2CH, Me3C) with [(S)-MeCHRCH2]3Al (II; R = Et, Me2CH, Me3C) 1 h at 0.degree. in pentane gives >70% RCH(OH)Ph (III; R = Et, Me2CH, Me3C).There are some commonly used reagents with their cas registry numbers 938-16-9 and 62916-84-1 in this article. (S)-III is prepd. in all cases except for the reaction of I (R = Me3C) with II (R = Me3C) which selectively gives (R)-III (R = Me3C). The optical yield of (S)-III (R = Et) in the redn. of I (R = Et) increased with the steric effect in II; this was not true for I (R = Me2CH, Me3C). The stereoselectivity is related to the conformation of the diastereoisomeric transition states. .

Asymmetric reduction with chiral reagents from lithium aluminum hydride and (S)-(-)-N-(o-substituted benzyl)-

Asymmetric reduction with chiral reagents from lithium aluminum hydride and (S)-(-)-N-(o-substituted benzyl)-.alpha.-phenylethylamines. Yamaguchi, Shozo; Yasuhara, Fujiko; Kabuto, Kuninobu (Coll. Gen. Educ., Tohoku Univ., Sendai, Japan). J. Org. Chem., 42(9), 1578-81 (English) 1977. 61491-38-1 and 938-16-9 which are cas registry numbers are also used here. CODEN: JOCEAH. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) Asymmetric redn. of carbonyl compds. with chiral hydride reagents modified by (S)-(-)-N-RCH=NCHMePh (R = Ph, 2-MeC6H4, 2-Me2NC6H4, 2-MeOC6H4, 2-MeSC6H4, 2,4,6-Me3C6H2) in PhMe was examd. to clarify the role of the functional group in the amine ligands on the stereoselectivity. Of the functional groups tested, the Me2N group exerted the greatest effect on the asymmetric redn. of ketones, affording fairly good optical yields [PhCH(OH)Me, 43% ee (sic); PhCH(OH)Et, 52% ee, and PhCH(OH)Bu-t, 47% ee]. The presence of additives such as MeOCH2CH2OMe or Me2NCH2CH2NMe2 in the reaction mixt. caused a dramatic decrease in the stereoselectivity, while that of MeSCH2CH2SMe did not. Chelate ring formation in the chiral hydride reagent is one of the essential factors for the high stereoselectivities obsd. .