Diastereo- and Enantioselective Synthesis of Polyfunctional Cyclic Ketones with Neighboring Quaternary and Tertiary Stereogenic Centers via [2,3]-Wittig Rearrangement
摘要:
介绍了通过 SAEP-hydrazones 2 的不对称 [2,3]-Wittig 重排,非对映地和对映体选择性地合成具有邻近四元和三元立体中心的δ²-取代δ³,δ-不饱和环状δ-羟基酮 4 的方法,该方法具有良好的总收率(58-74%)、高反选择性(92-94%)和优异的对映体过量(ee ≥ 96%)。通过对腙 3b 的 X 射线结构分析和 1H NMR NOE 测量确定了其绝对构型。
Concise synthesis of AHMHA unit in perthamide C. Structural and stereochemical revision of perthamide C
摘要:
Diastereomers of 3-amino-2-hydroxy-6-methylheptanoic acid (AHMHA), a new amino acid unit in perthamides C and D, have been synthesized from commercially available 4-methylpentanol in a concise manner and 50% average overall yield. Comparison of the H-1 and C-13 NMR data, optical rotation data and Marfey's analysis of the resulting isomers with the natural fragment unambiguously allowed the configurational assignment of the natural residue as (2R,3R). A structural revision of perthamides C and D is also reported. (C) 2010 Elsevier Ltd. All rights reserved.