Journal of Organic Chemistry p. 827 - 831 (1993)
Update date:2022-08-11
Topics:
Georghiou, Paris E.
Ren, Yi
Bridson, John N.
The synthesis of 4,4-dimethyl-1α,5α-cyclocholesta-3,7-dione (11), by lithium- or ytterbium-liquid ammonia reduction of the bis-α,β-unsaturated ketone, 4,4-dimethylcholesta-1,5-diene-3,7-dione (10), is described.The chemistry of the reductive cyclization is discussed.The 1H NMR spectra of the corresponding dihydroxy derivatives of 11 reveal an unusually high-field signal due to H-9.X-ray diffraction analysis of the 7β-monool 13a indicates that ring B of the steroid nucleus is in a boat conformation and that H-9 partially eclipses the C-1-C-10 bond of the cyclopropyl ring.An anisotropic ring current effect is postulated to account for the chemical shifts of H-9 in these cyclosteroids.The chemistry of these compounds is described.
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