Wurtz dehalogenation

Cyclogermanes. Cyclogermanes are prepared by methods similar to those used for polysilanes, for example, Wurtz dehalogenative coupling." Cyclogermanes (R2Ge) with n = 3, 4, and 5 can be isolated." ... 

Another group of reactions can be classified as intermolecular dehalogenations or dehydrohalogenations, based on Wurtz-, Fittig-, Ullmann-, Grignard-, or Friedel-Crafts reactions. Thus, polyphenylenes may be obtained by polycondensations of p-dichlorobenzene in the presence of Na/K alloy83-85. ... 

In the case of MePhSiCb, the Wurtz coupling dehalogenation produces three fractions, containing low-molecular weight cyclics, intermediate molecular weight cyclic oligomers, and high polymeric materials." ... 

A classical method using Na- or Li-liquid ammonia (Birch reduction conditions) is effective for reductive dehalogenations of aryl and vinylic halides, but it is not always successfully applied to alkyl halides, although cyclopropyl halides and bridgehead halogens are exceptions.Under such conditions, the reactions are often accompanied by side reactions, such as elimination, the Wurtz coupling reaction, cyclization and reduction of carbonyl compounds. An example, a synthesis of pentaprismane (1), is shown in Scheme 4. ... 

Dehalogenation.1 Cuprous chloride dissolves in DMSO to give a colorless clear solution, which reacts with certain benzylic and allylic halides to give products of Wurtz-type condensation. 

The first polysilanes were synthesized more than 75 years ago by Kipping through Wurtz-type reductive dehalogenation of dihalodiorganosilanes. This procedure, which is alkali metal intensive, has in the last decade been better understood and has consequently acquired a degree of control that was not previously considered possible. It remains the easiest and most widely used route to a polysilane and it will be discussed later in this section after consideration has been given to three other methods of synthesis that have been researched in recent years. 

Metal-assisted dehalogenation reaction, analogous to the well-known Wurtz reaction has been very effectively employed for the preparation of polysilanes which contain catenated organosilicon units. Thus, the reaction of a variety of diorganodichlorosilanes with finely divided sodium in a... 

---