Menthylphosphinites

In the 1990s phosphine boranes began to displace phosphine oxides as synthetic intermediates. Not surprisingly, P-stereogenic menthylphosphinite boranes were prepared, separated into pure diastereomers and subjected to analogous reactions as menthylphosphinates discussed in the previous section. These transformations are summarised in Scheme 2.20. 

Scheme 2.20 Preparation and reactivity of optically pure menthylphosphinite boranes.

Table 2.11 Phosphine boranes 54 prepared via nucleophilic substitution on menthylphosphinite boranes 53 (Scheme 2.20).

Mikolajczyk and co-workers reacted racemic ethylphenylchlorophosphine (rac-65) with menthol in presence of several bases to afford the corresponding menthylphosphinite 66 as a mixture of diastereomers (Scheme 2.24). 

Scheme 2.25 Preparation of P-stereogenic menthylphosphinites and phosphines from 70.

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