Chiral oxazaphosphorinanes, derived from (-)-8-amino menthol are alkylated with good
to excellent diastereoselectivities. The regioselectivity in the alkylation is dependent
on the base used for deprotonation. The ethyl oxazaphosphorinanes are alkylated at
the nitrogen substituent after deprotonation with n-butyllithium, but in α-position to the phosphorous atom by deprotonation with LDA.
On the contrary, the oxazaphosphorinanes with an alkyl substituent at the nitrogen
atom or benzyl oxazaphosphorinane are alkylated in α-position to the phosphorous atom
after deprotonation with either n-butyllithium or LDA.
alkylation - asymmetric synthesis - diastereoselective reactions - phosphonamidates
- phosphonates