Nair Vijay, Vellalath Sreekumar, Poonoth Manojkumar, Mohan Resmi, Suresh Eringathodi
Organic Chemistry Section, Regional Research Laboratory (CSIR), Trivandrum 695 019, India.
Org Lett. 2006 Feb 2;8(3):507-9. doi: 10.1021/ol052926n.
[reaction: see text]. Nucleophilic heterocyclic carbene (NHC) catalyzed annulation of enals and cyclic 1,2-dicarbonyl compounds, opening a route to gamma-spirolactones, has been observed for the first time. The strategy works well with isatins, leading to spiroannulated oxindole derivatives. It is conceivable that the spiroannulation protocol reported herein will be applicable to the synthesis of important natural products that are endowed with a spiro gamma-butyrolactone motif, especially oxindoles and norsesquiterpenoids.
[反应：见正文]。首次观察到亲核杂环卡宾（NHC）催化烯醛与环状1,2-二羰基化合物的环化反应，开辟了一条通往γ-螺内酯的途径。该策略对异吲哚酮效果良好，可生成螺环化的氧化吲哚衍生物。可以想象，本文报道的螺环化方案将适用于合成具有螺γ-丁内酯基序的重要天然产物，特别是氧化吲哚和去甲倍半萜类化合物。
