1723-55-3Relevant articles and documents
-
Halford,Weissmann
, p. 30,33 (1953)
-
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.
Regioselective Diels-Alder Addition to 2-Benzopyran-3-ones; a Route to Aromatic Steroids
Bleasdale, David A.,Jones, David W.
, p. 1027 - 1028 (2007/10/02)
2-Benzopyran-3-one (1; X=H) undergoes strongly regioselective Diels-Alder additions to buta-1,3-diene, isobutene, but-1-ene, and the olefin (6); the adducts derived from (6) and either (1; X = H) or (1; X = OMe) are readily transformed into the aromatic steroids: (9), (10), (17), (18), 9-epi-(10), 9-epi-(18), the naphthalene (14), and the dihydronaphthalene (15).
