Diastereoselective Preparation of Substituted δ-Valerolactones. Synthesis of (3<i>R</i>,4<i>S</i>)- and (3<i>R</i>,4<i>R</i>)-Simplactones
作者:Antonio Osorio-Lozada、Horacio F. Olivo
DOI:10.1021/jo8025548
日期:2009.2.6
were achieved in 5 steps from N-acyl thiazolidinethione chiral auxiliaries. The syntheses feature a double diastereoselective acetate aldol reaction solely controlled by the chirality of the auxiliary. Highly diastereoselective aldol reactions with s-trioxane were also achieved with N-acyl thiazolidinethione auxiliaries and the stereochemistry of an aldol product confirmed by X-ray analysis.
[GRAPHICS]Synthetic studies toward the total synthesis of (+)-acutiphycin (1) resulted in the discovery of additive-free, highly regioselective nickel -catalyzed reductive coupling reactions of aldehydes and 1,6-enynes and the construction of an advanced intermediate in studies directed toward the synthesis of 1. Ultimately, although not employing the nickel-catalyzed reaction, a highly convergent total synthesis of (+)-acutiphycin featuring an intermolecular SMI2-mediated Reformatsky coupling reaction and macrolactonization initiated by a retro-ene reaction of an alkoxyalkyne was achieved. The resulting synthesis was 18 steps in the longest linear sequence from either methyl acetoacetate or isobutyraldehyde.