Lithium Amino Alkoxide–Evans Enolate Mixed Aggregates: Aldol Addition with Matched and Mismatched Stereocontrol
作者:Janis Jermaks、Evan H. Tallmadge、Ivan Keresztes、David B. Collum
DOI:10.1021/jacs.7b13776
日期:2018.2.28
Building on structural and mechanistic studies of lithiated enolates derived from acylated oxazolidinones (Evans enolates) and chiral lithiated amino alkoxides, we found that amino alkoxides amplify the enantioselectivity of aldol additions. The pairing of enantiomeric series affords matched and mismatched stereoselectivities. The structures of mixed tetramers showing 2:2 and 3:1 (alkoxide-rich) stoichiometries
Microwave spectrum, molecular structure and dipole moment of pivalaldehyde
作者:A. Peter Cox、Andrew D. Couch、Kurt W. Hillig、Marabeth S. LaBarge、Robert L. Kuczkowski
DOI:10.1039/ft9918702689
日期:——
The microwave spectra of eight isotopic species of pivalaldehyde [(CH3)3CCHO] have been studied in the frequency region 9–40 GHz. The zero-point average skeletal structure has been derived to be: r[C(1)O]= 1.206(6)Å, r[C(1)–H]= 1.130(5)Å, r[C(1)–C(2)]= 1.516(7)Å, r[C(2)–C(3)]=r[C(2)–C(4),(5)]= 1.537(2)Å, ∠ C(1)C(2)C(3)= 110.5(4)°, ∠ C(1)C(2)C(4),(5)= 107.4(3)°, proj.∠ C(4),(5)C(2)C(1)= 120.78(4)°,