135875-60-4Relevant academic research and scientific papers
2-Benzopyran-3-ones as Synthetic Building Blocks; Regioselective Diels-Alder Additions with Simple Olefins leading to Aromatic Steroids
Bleasdale, David A.,Jones, David W.
, p. 1683 - 1692 (2007/10/02)
2-Benzopyran-3-one 1a undergoes strongly regioselective Diels-Alder additions to buta-1,3-diene, 2-methylpropene, but-1-ene and the olefin 9.The main adducts 17a and 17b from 1a and 1b respectively and the olefin 9(=16) are derived by endo- and exo-addition to the re-face of 9(=16).These adducts are converted into the 8α,9α-steroids 22a and 22b by a four-step sequence including Dieckmann cyclisation of 21a and 21b as the key step.The derived 8α,9α-steroids 24a and 24b can be epimerised at C-8 via the enones 26a and 26b and lithium-ammonia reduction.Other aromatic steroids obtained by this general route are the equilenin derivative 28 and the dihydronaphthalene 29.
