The Application Of Organozinc Reagents With α,α-Dihalo-ketones And Halo Ketone

Organozincs are an important class of organometallics for organic synthesis and organometallic synthesis. Investigation in recent years shows that the organozincs can react with a lot of electrophiles. Moreover, some functional groups can exisit in the reagent and be directly introduced into target molecules. The application of organozinc reagents in organic synthesis has been attracted more attention.The thesis consists of the following two sections:1. Zinc is a relatively inexpensive, non-toxic metal. The low activity of organic zinc reagents, once considered a major impediment, has now become one of their greatest assets. The reaction of organozinc reagents withα,α-dihalo-ketones have been attracted our attention. A series ofα,α-dihalo ketones were prepared as substrate, and its reaction with organozinc reagents was carried out. The experiment showed that: (a) theα-halo,α-allylic-aldehydes were efficiently obtained in moderate yields in the presence of DMF; (b) these compounds had considerable significance in theoretical and synthetic organic chemistry; (c) the products containing a carbon atom bearing three or four different labile functional groups, these compounds usually difficult to prepare, a one-pot method for preparation of this kind of compounds is developed; (d) substituted allylic zinc reagents selectively attacks the carbonyl group; (e) substituted allylic zinc reagents is added toα,α-dihalo ketones despite the steric hindrance; (f) a possible mechanism of the transformation is proposed.2. The only products epoxides were obtained in the reaction of allylzinc bromide reagents withα-halo ketones under the proper conditions in the presence of DABCO.