Dimethylphosphine boranes

This method is not only restricted to dimethylphosphine boranes and sulfides. It has been also applied to cyclic diphosphine derivatives by deprotonation of one of the enantiotopic methylene groups a to the phosphorus atom (Scheme 5.3). In this case, a second stereogenic centre is created and therefore it is necessary to control also the diastereoselectivity of the reactions. 

In 1995 Evans and co-workers reported the first synthetically useful enantioselective deprotonation lectrophilic quenching of dimethylphosphine boranes (Scheme 5.4). 

Evans and co-workers described the preparation of 1,2-ftjXarylmethyl-phosphine borane)ethanes by oxidative coupling of anions derived from aryl-dimethylphosphine boranes with Cu(II) pivalate (Scheme 5.19). 

Both methylphosphine (this synthesis) and dimethylphosphine (the following synthesis) are considerably stronger Lewis bases than phosphine, and their reactions with various Lewis acids, including boranes, have been the subject of recent studies. Both methylphosphine and dimethylphosphine are readily oxidized by air, and thus can serve as sources of methylphos-phonous (methylphosphinic) acid, CH3PHO(OH), and dimethyl-phosphinic acid, (CH3)2PO(OH). ... 

Ammonia reacts with trifluorophosphine borane at low temperatures to give the tris amino derivative (9.14). The tris dimethylamino analogue is made from sodium borohydride, carbon dioxide and the appropriate phosphine (7.85). Dimethylamino dimethylphosphine reacts with diborane at -78°C to give an addition compound (9.15), which, on heating, decomposes to give a variety of products. 

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