A divergent asymmetric approach to aza-spiropyran derivative and (1S,8aR)-1-hydroxyindolizidine

• Jian-Feng Zheng,
• Wen Chen,
• Su-Yu Huang,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2007, 3, No. 41, doi:10.1186/1860-5397-3-41

• methodology. Background Spiroketals of general structure A (Scheme 1) constitute key structural features of a number of bioactive natural products isolated from insects, microbes, fungi, plants or marine organisms. [1][2][3] The corresponding aza-spiroketal (cf: general structure B) containing natural

• stereoselectively to either hydroxylactams F or G under appropriate conditions. [36][37][38] It was envisioned that if a C4-bifunctional Grignard reagent was used, both aza-spiroketal H (such as aza-spiropyran, n = 1, path a) and indolizidine ring systems I (path b) could be obtained. The synthesis of aza