Synthesis of Steroidal Heterocycles

Steroids: reactions and partial syntheses

“…(67)J arose from attack of the solvent on the intermediate vinyl cation. Treatment of 16a, 17ct-dimethyl-carboxylic esters (68) or -ketones (69) with MeMgX was reporteds3 to give the ethynylcompounds (71) via the enolate (70). The nitrones (72) were readily prepared from the 3-ketones and some of their reactions have been described, including deoxygenation to the imines with H2S.84 The a-hydroxynitrone (73) has been converted into the 18-0x0-oximinobenzoate (74), allowing selective reactions at C-18.8s Oxidation of the pyrrolinium salt (75) with p-nitroperbenzoic acid gave the oxaziridinium salt (76) whereas with HzOz there was no reaction.…”

Oxazole chemistry. A review of recent advances

“…A review covering the synthesis of steroidal heterocycles including oxazolosteroids has appeared (320). An interesting example of the synthesis of an oxazole-containing steroid was reported by Wolloch and Zbiral, who obtained the oxazoles 642 by treating 2-azidocholestane-3-one (641) with acid anhydrides in the presence of triphenylphosphine (321).…”

Recent Reviews

“…Resolution, optical strategies, 265 RNA, transfer in protein synth, 257 Rubber, vulcanization, 319 Ryanodine, synth, 213 Sandwich cmpds, 61 Selenium dioxide oxidn, 154 Silicon cmpds, anionic rearr, 38 d-orbitals, 375 /j-functionalized, 19 by hydrosilylation, 225,338 Silylated enolates in synth, 241 Smoke, tobacco, nitrogen cmpds, 87 Solid state, organic, topochem, 54 Spin relaxation I3C NMR, 278 Spin-spin coupling, indirect 13C NMR, 280 Stenhouse salts, use, 253 Stereodifferentiating reactions, 373 Stereochemistry, classical foundations, 281 Stereochemistry, heterocycles, 367 Stereochemistry, mass spectrometry, 282 metal redn ketones, 197 Steric effects, ketones, 196 P ligands in organometallics, 88 quant model, 167 Steric interactions, substituents, 69 Steroids, biochem, 379 crystal structure, 285 heterocyclic, 133 uncommon marine, 316 Strain energy modelling, crowded ketones,…”