A short, stereoselective, and common approach for the synthesis of 4,5-disubstituted δ-lactones simplactone B and its C-5 analogue
作者:A. Ravi Kumar、N. Sudhakar、B. Venkateswara Rao、N. Raghunandan、A. Venkatesh、M. Sarangapani
DOI:10.1016/j.bmcl.2005.02.059
日期:2005.4
A short, stereoselective, and a common approach for the synthesis of 4,5-disubstituted delta-lactones simplactone B and itsanalogue using Evans protocol is described.
Starting from enantiopure 4-cumyloxy-2-cyclopenten-1-one, a route to 5- and 6-substituted hyropyran-2-ones has been developed. The method has achieved the synthesis of 4,5-cis- and 4,5-trans-5-ethyl-4-hydroxytetrahydropyran-2-ones assigned to marine natural products simplactones A and B to disprove the former and revise the latter of the proposed structures.
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.
A new, simple, and short route for the synthesis of simplactones A (1) and B (2) was achieved from a synthetically prepared chiral auxiliary, i.e., the Oppolzer camphor‐derived sultam 4, and (4‐methoxybenzyl)‐protected 3‐hydroxypropanal, in 52 and 48% overall yield, respectively, and with high diastereoselectivity (Schemes 2 and 3).