Reactions involving P—C Bond Cleavage

The phosphine oxide (38) is known to undergo nucleophilic substitution reactions with cleavage of either a phosphorus-phenyl bond, or one of the heterocyclic 

Primary amines react with benzylbis(a-hydroxybenzyl)phosphine oxide (39) to give a-aminoalkylphosphine oxides (40) and (41 ),34 and the reaction has been 

Details of various routes to allylphosphine oxides (43) have been reported, and the subsequent synthesis of 1,3-dienes has been illustrated by many examples.37 Also described are stereochemical aspects of these diene syntheses and of subsequent Diels-Alder cycloaddition reactions.37 High regioselectivity is observed in migrations of the diphenylphosphinoyl group from unsymmetrical sites, as in (44), in that both products have a double bond exocydic to the cyclohexane ring.38 

Migration of sulphur from one phosphorus to another has been observed39 when the sulphide (45) is heated. The intermediates (46) and (47) have been detected. Debenzyl-ation of the phosphine sulphide (48) has been shown to be accompanied by a desulphuration, which is believed to result from the interaction of (49) with alkaline DMSO.40 

Several examples have been reported of rearrangements of arsine oxides (51) to esters, initiated by alkyl halides.42 43 Reactions of tertiary arsine oxides with thiols (52) cause deoxygenation.44 

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