Pregnanes and androstanes are described which essentially possess a 3.alpha.-hydroxy group, a 5.alpha.-hydrogen atom or a 4.5- or 5,6-double bond, a 17.alpha.-hydrogen atom and an 11.beta.-aminoester group. Other optional substituents or double bonds may be present. The compounds have anaesthetic activity.
Diiodosilane. 4.<sup>1</sup>Direct Reduction of Ketals and Acetals in the Presence of Unprotected Carbonyls. A Case of Inverted Chemoselectivity
作者:E. Keinan、M. Sahai、R. Shvily
DOI:10.1055/s-1991-26533
日期:——
Ketals and acetals are selectively reduced by diiodosilane to iodoalkanes in preference to ketones and aldehydes. This inversion of the normal order of reactivity of the "protected" and "unprotected" carbonyls allows partial reduction of polycarbonyl compounds with unusual regio- and chemoselectivity. Thus, 8,8-(ethylenedioxy)octan-2-one, 7,7-(ethylenedioxy)octanal, 3,3-(ethylenedioxy)-androstan-17-one and 3,3-(ethylenedioxy) pregnane-11,20-dione are converted to the corresponding iodo compounds.
-one), the principal neurosteroid acting via γ-aminobutyric acid (GABA). These analogues were designed to study the structural requirements of the corresponding GABAA receptor. Their biological activity was measured by in vitro test with [3H]flunitrazepam as radioligand in which allopregnanolone and its active analogues stimulated the binding to the GABAA receptor. Analysis of the SAR data suggests