Synthesis of a Novel 1α,5α-Cyclocholestane

Article abstract of DOI:10.1021/jo00056a012

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.