Various diazo compounds, nitrile oxides, nitrones and azomethine ylides were examined in 1,3-dipolar cycloadditions to enantiomerically pure 5-(R)-menthyloxy-2(5H)-furanone 1a. Pyrazoline 9 was obtained in 100% c.y. as a mixture of 2 diastereoisomers in ratios up to 72: 28, whereas pyrazoline 16 was …

The lanthanide alkyls Cp 2 *LnCH(SiMe 3 ) 2 (Ln = La, Ce) are efficient catalysts for the cyclodimerization of 2-alkynes MeC≡CR (R = Me, Et, n-Pr) to 1,2-disubstituted 3-alkylidenecyclobutenes. The first step in the reaction is a propargylic metalation of the α-methyl group, giving Cp* 2 LnCH 2 C≡CR …

On the basis of a model for energy budgets, which includes the dynamics of stored energy, a model has been proposed for the kinetics of non-metabolized xenobiotic compounds, which may be lipophilic. The surface area coupled uptake is via food and/or water through the aqueous fraction of the animal. The …