The Application Of Allylsamarium Reagent In The Synthesis Of Distant And Conjugated Multiolefins

The application of samarium reagents in organic synthesis has been attracted more attention. It benefits to develop further the high selective reaction by samarium reagents. The thesis consists of the following two sections:1. Compared to allylmagnesium bromide, allylsamarium bromide has much lower reactivity, and it does not give rise to coupling byproduct during preparation. Especially, it has excellent selectivity. Moreover, the samarium atom of allylsamarium bromide is still divalent, and we think that it can transfer a single electron to reduce the suitable substrate leading to steady trivalent samarium. However, there is no an example of the application of allylsamarium bromide as a single electron transfer reagent. A series ofα-halo esters andγ-halo-α,β-unsaturated carbonyl compounds were prepared as substrates, and their reaction with allylsamarium bromide were carried out. The experiment showed that allylsamarium bromide selectively attacks the carbonyl group, followed by a sequential single electron transfer to afford distant multiolefins. To the best of our knowledge, it is the first application of allylsamarium bromide as a single electron transfer reagent in the reaction. From a synthetic point of view, a general, efficient, and experimentally simple method for preparation of distant multiolefins is developed. And a possible mechanism of the transformation is proposed.2. We proposed a new, facile and one-pot synthesis of conjugated multiolefine compared to traditional synthesis of it, especially for high impediment conjugated multiolefine.