Deuterium oxide sulphones

Still has also carried out mechanistic experiments9 3 from which he could deduce that the major reduction pathway is by attack of hydride ion at the sulphur atom. This conclusion was deduced from the fact that reduction with sodium borodeuteride-aluminium oxide gave a sulphoxide that had only incorporated about 25% mole equivalent of deuterium on to a methyl carbon atom bound to the sulphur atom. The mechanistic pathway for direct reduction is outlined in equation (38), whereas the pathway whereby deuterium could be incorporated is portrayed in equation (39). These reactions support the proposed mechanism for the hydride reduction of sulphones as outlined in Section III.A.l, namely that attack at sulphur by hydride ions may occur, but will be competitive with proton abstraction in cases when the attack at sulphur is not facilitated. 

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