Beilstein J. Org. Chem.2016,12, 2816–2822, doi:10.3762/bjoc.12.280
Abstract We have synthesized a series of cis-6a,7,8,12b-tetrahydro-6H-naphtho[2,1-c]chromen-6a-ols as B-ring-modified analogues of (±)-brazilin. A completely regio- and cis-diastereoselective intramolecular Friedel–Crafts epoxy–arene cyclization of 1-tetralone-derived glycidyl ethers catalyzed by Brønsted
been reductively removed by a diastereoselective method which should be useful in future for preparing libraries of chroman-fused tetralins with trans-stereochemistry at the ring junction.
Keywords: brazilin; chroman; epoxy-arene cyclization; natural-product-like molecules; tetralin; Findings
The
chroman unit occurs widely as a privileged framework in a large number of natural products (NPs), natural product-like molecules (NPLMs) and pharmaceuticals, possessing diverse biological activities [1]. (+)-Brazilin (1) and (−)-haematoxylin (2) are two structurally-related tetracyclic homoisoflavonoid
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Graphical Abstract
Figure 1:
Chroman-based tetracyclic natural products 1–4 of the brazilin family and our designed, B-ring-modi...
Beilstein J. Org. Chem.2012,8, 1999–2003, doi:10.3762/bjoc.8.226
effective in the treatment of various conditions, such as diarrhea, dysentery, dyspepsia, leucorrhea, and diabetic complications [9][10]. The main components of H. campechianum and C. sappan are hematoxylin (3, Figure 1) and brazilin; the basic structures of the two contain a 3,4-cycloalkyl-fused benzopyran