Abstract
A new homo-proline tetrazole derivative 7 has been prepared and shown to have improved properties for achieving asymmetric Michael addition of carbonyl compounds to nitro-olefins.
Key words
asymmetric - nitro-Michael - organocatalysis - homo-proline - tetrazole
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9
Typical Experimental Procedure.
i -PrOH-EtOH mix (1:1, 2 mL) was added ketone (0.75 mmol, 1.5 equiv) and the resulting mixture stirred at 20 °C for 24 h. After this time the reaction was quenched with sat. NH4 Cl (2 × 20 mL) and the aqueous phase extracted with EtOAc (2 × 25 mL). The combined organic layers were dried (MgSO4 ), filtered and evaporated to give a residue which was further purified by flash column chromatography using EtOAc and petroleum ether 40-60 as eluent.
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12 This was proven by comparison of chiral HPLC retention times and also by an inversion of sign in the optical rotation as compared to literature.
