A study of the Stork reductive cyclization of steroidal acetylenic ketones in aprotic media with the naphthalene anion radicals

Formation of the steroidal 3β-hydroxy-6-oxo-moiety. Synthesis and cytotoxicity of glucolaxogenin

“…The radical anion sodium naphthalenide (SN) is a one electron donor, easy to prepare. 12 The SN promotes reactions as the reductive cyclization of steroidal acetylenic ketones, 13 coupling of ketones 14 and thiocarbonyl functionalities; 15 converts vicinal cyanohydrins and geminal dihalides into olefins, 16 and removes p-toluensulfonamide, mesylate and tosylate protecting groups among others. 17 The reaction conditions in the reductive cleavage of tosylates by means of SN have been widely studied as aforementioned, finding that vicinal groups have influence in the reaction pathway.…”

“…1 H and 13 C NMR spectra were recorded at 400 and 100 MHz respectively on a Varian Mercury spectrometer. The spectra were registered in CDCl 3 and referenced to TMS.…”

Single Electron Transfer in Radical Ion and Radical-Mediated Organic, Materials and Polymer Synthesis

“…The deficiency of this chemistry is the low control of stoichiometry of solvated electrons in the Stork cyclization reaction . A modification was subsequently made to use the naphthalene radical anions as donors to improve the yield …”

“…94 A modification was subsequently made to use the naphthalene radical anions as donors to improve the yield. 488 3.2.3.2. Distonic Radical Anions Formed by SmI 2 .…”

Radical ion cyclizations

“…In contrast, electroreductive cyclization of 184 does not lead to 185, but exclusively to the thermodynamically preferred 5-exo isomer with a remaining double bond in the endocyclic position [185] (Scheme 35). The steroid precursor 4.5-secocholestan-5-one 187, in which the 10a-side chain is varied, has been cyclized under the same conditions [186][187][188] bond; whereas, if alkali metal in ammonia is used, the cyclization is accompanied by simple reduction to a secondary alcohol. In the first step, the mechanism certainly involves one-electron reduction to form the ketyl radical anion.…”