TL;DR: A review of selective reactions and modifications for the partial and total synthesis of steroids can be found in this paper, with a focus on tricyclic intermediates in total synthesis.
Abstract: THE last ten years have seen a concentrated effort in the partial and total synthesis of steroids, occasioned in particular by the discovery of the adrenocortical hormones and of their physiological activity. This effort has involved conducting selective reactions on multifunctional compounds, and protection of one type of functional group against the consequence of reactions aimed at another. It seems desirable to give a review of such selective reactions and modifications; not only for the benefit of workers in the steroid field itself, but also as a guide for those working in other fields of organic synthesis, some of whom tend to assume that steroid chemistry is an exclusive domain. This review covers the more important literature from 1948 through 1957, but it is not intended to be exhaustive. Work on tricyclic intermediates in steroid total synthesis has been included, but facts published in communication form are not dealt with unless such communications mention a modicum of experimental detail.
TL;DR: Results support the supposition that oxysterols may regulate sterol biosynthesis at the cellular level and include the inhibitory effects of 9α, 11α-epoxycholest-7-en-3β-ol cholest
Abstract: As a class of compounds, oxysterols have demonstrated a wide variety of biological properties. Due to the general interest in these compounds, new methods of chemical synthesis have been developed to provide them for biological investigation. The specific inhibition by oxysterols of cholesterol biosynthesis in mammalian cells has been shown to result primarily from a decrease in cellular levels of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity. Recent evidence suggests these cellular responses may be mediated by an oxysterol binding protein found in the cytosol of many lines of cultured cells. In certain instances, oxysterols have been shown to be produced in biological systems. These results support the supposition that oxysterols may regulate sterol biosynthesis at the cellular level. Included herein are the inhibitory effects of 9α, 11α-epoxycholest-7-en-3β-ol cholest-8-en-3β-ol-7-one and cholest-8-en-3β-ol-11-one on HMG-CoA reductase activity and their relative affinities for a cytosolic binding protein.
TL;DR: In this paper, the tetrahydropyranyl (THP) group was efficiently removed using PdCl 2 (CH 3 CN) 2 as catalyst in CH 3 CN, while other protection groups such as p -toluenesulfonyl (Ts), tert-butyldiphenylsilyl (TBDPS), benzyloxycarbonyl, allyl, benzyl (Bn), and benzoyl (Bz) remained intact under these conditions.
Abstract: Primary alcohols were selectively tetrahydropyranylated in good to excellent yields at room temperature using PdCl 2 (CH 3 CN) 2 as catalyst in tetrahydrofuran (THF) in the presence of phenols, secondary, and tertiary alcohols. The tetrahydropyranyl (THP) group could be efficiently removed using PdCl 2 (CH 3 CN) 2 as catalyst in CH 3 CN, while other protection groups such as p -toluenesulfonyl (Ts), tert -butyldiphenylsilyl (TBDPS), benzyloxycarbonyl (Cbz), allyl, benzyl (Bn), and benzoyl (Bz) remained intact under these conditions.