Organometallics to activated double bonds

Addition of Organometallic Compounds to Activated Double Bonds Hydro-alkyl-addition... 

Organometallic compounds and alkoxides add to activated double bonds and to functional groups such as ketones, esters, nitriles, and aldehydes. Many workers have taken advantage of this tendency and have attempted to prepare graft polymers by this method (2). A detailed description of these techniques and others like it is given in a recent review by Heller (3). 

Nevertheless, there are promising strategies which may help to overcome these problems, for example, the use of less basic organometallics and/or the activation of the C-N double bond by Lewis acids. Therefore, it is not particularly surprising that the number of publications dealing with the stereochemical aspects of these reactions increases continuously. 

Thiazolinc 2 proves to be inert to organometallic attack. However, addition of organolithium and Grignard reagents to the C —N double bond of 2 can easily be achieved by previous activation with boron trifluoridc, providing /r[Pg.696]

Undoubtedly, the most notable feature of these new dendrimeric organometallic molecules is their ability to act successfully as effective homogeneous catalysts for the Kharasch addition reaction of polyhalogenoalkanes to olefinic C=C double bonds. Indeed, they show catalytic activity and clean regiospecific formation of 1 1 addition products in a similar way to that observed in the mononuclear compounds. Likewise, the nanoscopic size of these first examples of soluble dendritic catalysts allows the separation of such macromolecules from the solution of the products by ultrafiltration methods. 

---