Stereoselective Alkylation of Lithium Enolates Generated from<i>t</i>-Butyl Esters of 4-Alkyl-Substituted 5-Hydroxypentanoic Acids
作者:Yutaka Ukaji、Koichi Narasaka
DOI:10.1246/bcsj.61.571
日期:1988.2
Alkylation of lithiumenolates generated from t-butyl esters of 4-alkyl-substituted 5-hydroxypentanoic acid by treatment with lithium pyrrolidinide in THF–HMPA proceeded stereoselectively to afford the corresponding anti-α-alkylated esters.
only two conformations. Substituents have been varied in order to find those which lead to a strong preference of the conformer equilibrium. Studying 2-substituted 4-methylpentanes 3 and 4-benzyloxypentanes 12, it has been shown that substituent effects on the conformer equilibria are not additive, as would be expected on the grounds of steric effects alone. Rather, interactions between polar groups
Supellapyrone [(2R,4R)-5-(2,4-dimethyl)-3-methyl-2H-pyran-2-one (1)], the female sex pheromone of the brownbanded cockroach (Supella longipalpa), and its three stereoisomers were synthesized by employing Iipase-catalyzed desymmetrization or enantiomer separation of syn- or anti-2,4-dimethylpentane- 1,5-diol (9) as the key step.
Erythromycin. XI.<sup>1</sup> Structure of Erythromycin B<sup>2</sup>
作者:Paul F. Wiley、Max V. Sigal、Ollidene Weaver、Rosmarie Monahan、Koert Gerzon
DOI:10.1021/ja01579a060
日期:1957.11
The Relative Stabilities of cis and trans Isomers. IV. The 3,5-Dimethylcycloheptanones<sup>1,2</sup>