Intramolecular direct dehydrohalide coupling promoted by KO(t)Bu: total synthesis of Amaryllidaceae alkaloids anhydrolycorinone and oxoassoanine.

Subhadip De, Santanu Ghosh, Subhajit Bhunia, Javeed Ahmad Sheikh, Alakesh Bisai

Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, MP-462023, India.

Organic letters 2012 Sep 7

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A transition-metal-free intramolecular dehydrohalide coupling via intramolecular homolytic aromatic substitution (HAS) with aryl radicals has been developed in the presence of potassium tert-butoxide and an organic molecule as the catalyst. The methodology has been applied to a concise synthesis of Amaryllidaceae alkaloids viz. oxoassoanine (1b), anhydrolycorinone (1d), and other related structures. Interestingly, the method also works only in the presence of potassium tert-butoxide.

Citation

Subhadip De, Santanu Ghosh, Subhajit Bhunia, Javeed Ahmad Sheikh, Alakesh Bisai. Intramolecular direct dehydrohalide coupling promoted by KO(t)Bu: total synthesis of Amaryllidaceae alkaloids anhydrolycorinone and oxoassoanine. Organic letters. 2012 Sep 7;14(17):4466-9