88790-26-5Relevant articles and documents
Felkin-Anh stereoselectivity in cycloadditions of acetylketene: Evidence for a concerted, pseudopericyclic pathway
Shumway,Ham,Moer,Whittlesey,Birney
, p. 7731 - 7739 (2007/10/03)
The cycloadditions of acetylketene with α-chiral aldehydes and ketones are shown to be diastereoselective, forming a tertiary or quaternary chiral center at an acetal or ketal carbon with good stereocontrol. X-ray crystallography of a minor product (5b) shows that the major products (e.g., 4b) are those predicted by the Felkin-Anh model. Transition states are reported at the MP2/6-31G* level for the addition of ethanal to formylketene and at the B3LYP/6-31G* level for the addition of 2-phenylpropanal. The ground-state conformations of the reactants and products are used to rationalize the relative energies and geometries of the transition states without the need to invoke the Cieplak hypothesis. However, chiral substituents on the α-oxoketene show no diastereoselectivity. These experimental and computational results are only consistent with the nearly planar, pseudopericyclic transition state previously proposed.
Zirconium Mediated Regioselective Carbon-Carbon Bond Formation Reactions
Takahashi, Tamotsu,Suzuki, Noriyuki,Hasegawa, Maki,Nitto, Yu,Aoyagi, Ko-ichiro,Saburi, Masahiko
, p. 331 - 334 (2007/10/02)
Reactions of zirconocene-alkene complexes with aldehydes gave alcohols as coupling products after hydrolysis.The carbon-carbon bond formation proceeded at C1 carbon of alkenes, in sharp contrast to the reactions of alkene-alkene coupling on zirconium.A similar alcohol was also obtained by the reaction of zirconacyclopentane with aldehyde after hydrolysis.Treatment of (C5Me5)2ZrEt2 with styrene gave 2-phenylbutane after hydrolysis contrary to the case of Cp2ZrEt2 which afforded 1-phenylbutane.
Highly Diastereoselective 1,2-Asymmetric Addition of Dialkylzincs to Chiral 2-Phenylpropanal Catalyzed by Amino Alcohol
Soai, Kenso,Niwa, Seiji,Hatanaka, Toshihiro
, p. 2129 - 2130 (2007/10/02)
Diastereoselective addition of dialkylzinc reagents to 2-phenylpropanal using amino alcohol as catalyst afforded erythro alcohols (Cram-selectivity) in high diastereomeric excess (up to 88percent d.e.).