The cause of the rate acceleration by diethyl ether solutions of lithium perchlorate (LPDE) in organic reactions. Application to high pressure synthesis

Article abstract of DOI:10.1016/S0040-4020(97)00172-5

Kinetic studies of isoprene cyclodimerization show that the accelerating effect caused by LPDE (solution of lithium perchlorate in diethyl ether) in some organic reactions cannot be ascribed to internal pressure of LPDE. The kinetic effect is essentially due to catalysis through Li⁺. Additional arguments are provided by comparison of yields obtained in LPDE (0.1 MPa) and in organic solvents (under pressure) for Diels-Alder reactions of various electronic types. Combination of high pressure and LPDE catalysis is revealed as an excellent multiactivation process to achieve difficult syntheses, but only for [4 + 2] cycloadditions.