155. Chiral toluene-2,α-sultam auxiliaries: Asymmetric alkylations, acylations and aldolizations of N-acyl derivatives
     Oppolzer, W.; Rodriguez, I.; Starkemann, C.; Walther, E.
     Tetrahedron Lett. 1990, 31, 5019-5022

Successive treatment of (R)-N-acylsultams 4 with NHDMS/alkyl halides or NHDMS/acyl chlorides provides alkylated or acylated products 6 or 7. Diastereoselective reductions of with Zn(BH₄)₂ or NaHB(sBu)₃ gives “syn”- or “anti”-aldols 8 or 9. Reaction of 4 with BEt₃/TfOH/EtN(iPr)₂ followed by addition of aromatic or aliphatic aldehydes affords diastereomerically pure “synrd-aldols 10. Non-destructive removal of auxiliary 3 from 6, 8, 9 and 10 yields enantiomerically pure products 12 to 16.

DOI : 10.1016/S0040-4039(00)97794-3 

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