Phosphoramidates alkene protection

S)-Nicotine (13) is one of the many piperidine and pyrroHdine alkaloids isolated from the leaves of Nicotaiana tabacum. Welter and coworkers developed a synthesis route where 13 was obtained in only four steps from pyridinylallyl carbonate 10 involving RCM (Scheme 2.4) [17]. The synthesis commenced with an Ir-catalyzed asymmetric allylic amination of 10 to produce bis-alkene 11 in excellent enantiomeric purity when using phosphoramidate Hgand LI. Subsequently, secondary amine 11 was N-protected to produce 12 prior to RCM in order to prevent catalyst... 

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