Asymmetric diastereoselectivity

The bis(oxazoline) S, 5)-(115) has been used as an external chiral ligand to induce asymmetric diastereoselective lithiation by r-BuLi during [2,3]-Wittig rearrangement of achiral substrates, (fj-crotyl propargylic ethers.It is believed that the enantios-electivity is determined predominantly at the lithiation step. 

Another substrate class, for which the outcomes of a radical and a carbocationic process are opposite, are indoles (Fig. 85) [418], Indeed, when oxaziridines 315a or 315c were treated with indoles 314c in the presence of 2 or 10 mol% of C11CI2/ TBAC oxazolidinoindolines 316c were obtained as the exclusive products in 53-90% yield. The reaction is applicable to 2-, 3-, and 2,3-disubstituted indoles. Chiral indole derivatives acylated with (S)-proline units at nitrogen underwent asymmetric diastereoselective aminohydroxylation reactions with 86-91% de. Tricyclic hemiaminals derived from tryptamine derivatives could be transformed to pyrrolidinoindolines, which are core structures of a number of alkaloids. 

Palladium-catalyzed palladium-ene/carbonylation methodology was also used in an asymmetric diastereoselective total synthesis of (+ )-3-isorauniticine (25) starting from the optically active dienyl carbonate 2371. 

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