An easy stereoselective synthesis of 5(10)-estrene-3β,17α-diol, a biological marker of pregnancy in the mare
5(10)-Estrene-3β,17α-diol is an essential reference material for doping analysis in horse-racing laboratories. It is used to detect misuse, for doping purpose, of the pregnancy status in the mare. Its stereoselective synthesis from 17β-estradiol-3-methyl ether (prepared from estrone or 17β-estradiol) was performed in four steps: (1) Mitsunobu inversion of the 17β-alcohol; (2) Birch reduction of the aromatic ring; (3) stereoselective reduction of the 3-ketone via Noyori asymmetric transfer hydrogenation; (4) chemoenzymatic purification.
Balssa, Frédéric,Fischer, Michael,Bonnaire, Yves
p. 1 - 4
(2014/06/09)
Neurosteroid analogues. 4. The effect of methyl substitution at the C-5 and C-10 positions of neurosteroids on electrophysiological activity at GABA(A) receptors
A series of analogues of the neuroactive steroids 3α-hydroxy-5α- pregnan-20-one and 3α-hydroxy-5β-pregnan-20-one were studied to elucidate the mode of binding of 5α- and 5β-reduced steroids to steroid binding sites on GABA(A) receptors. Analogues which were either 3α-hydroxy-20-ketosteroids or 3α-hydroxysteroid-17β-carbonitriles and which contained various methyl group substitution patterns at C-5 and C-10 were prepared. Evaluations utilized whole-cell patch clamp electrophysiological methods carried out on cultured rat hippocampal neurons, and the results obtained with the rigid 17β-carbonitrile analogs were analyzed using molecular modeling methods. The molecular modeling results provide a rationale for the observation that the configuration of the hydroxyl group at C-3 is a greater determinant of anesthetic potency than the configuration of the A,B ring fusion at C-5. The electrophysiological results identify steric restrictions for the space that can be occupied in 5α- and 5β-reduced steriod modulators of GABA(A) recepters in the regions of space proximate to the steroid C-5, C-10, and possibly C-4 positions. This information is useful for the development of nonsteroidal analogues that can modulate GABA(A) receptors via interactions at steroid binding sites.
Han, Mingcheng,Zorumski, Charles F.,Covey, Douglas F.
p. 4218 - 4232
(2007/10/03)
Facial selectivity in the hydroboration of androst-4-enes
In the absence of an allylic hydroxy group, the stereochemistry of hydroboration of an androst-4-ene is determined by the presence and stereochemistry of the C-10 methyl group.Allylic hydroxy groups at C-3 direct the hydroboration/oxidation to the anti-face.In the case of the 3α-alcohol, this effect is in opposition to the normal hydration from the α-face of the steroid and leads to the 4β-alcohol.The stereochemistry of 4β,17β-diacetoxy-19-nor-5β-androstane was established by X-ray crystallography.
Hanson, James R.,Hitchcock, Peter B.,Liman, Mansur D.,Naragatnam, Sivajini
p. 2183 - 2188
(2007/10/02)
More Articles about upstream products of 19793-20-5