Fang J, Fang J, Rao Y, Qiu H, Pan Z, Ma Y. Metal-free construction of dihydropyrazino[2,3-
b]indoles from 2-aminoacetophenones, isocyanates and 1,2-diamines.
Org Biomol Chem 2024;
22:2043-2048. [PMID:
38358007 DOI:
10.1039/d3ob01967e]
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Abstract
A Brønsted acid/iodine co-mediated approach to construct dihydropyrazino[2,3-b]indoles in 2-MeTHF as a green solvent at room temperature was established. A wide range of diversely substituted dihydropyrazino[2,3-b]indoles (42 examples, 61-85% yields) were synthesized under mild conditions, even on a gram scale. This protocol features organocatalysts, an eco-friendly solvent, mild conditions, readily accessible substrates, broad substrate scope and simple work-up.
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