Jesús Sandoval-Ramírez

Preparation of 22,26-epoxycholest-22-ene steroids. Novel transformation of the side chain in sapogenins

Abstract The one step conversion of the side chain in sapogenins into the 22,26-epoxycholest-22-ene framework was achieved in yields >85% using BF3·OEt2. The new structures maintain the natural chirality at C20 and C25, as shown by X-ray diffraction analyses.

The anomeric effect in 2-arylseleno-1,3-dithianes

Abstract The anomeric effect in a series of 2-(4-substituted-phenylseleno)-1,3-dithianes (substituents, R = NO2, CF3, H, OMe, NMe2) decreases in the sequence NO2>CF3>H>OMe>NMe2, providing systematic experimental evidence for the role of stabilizing orbital interactions.

A Convenient Synthesis of 4,4′-Dimethylaminodiphenyl Diselenide and 4,4′-Dinitrodiphenyl Diselenide

Abstract A simple, rapid and efficient synthesis of 4,4′-dimethylamino-diphenyl diselenide 1 and 4,4′-dinitrodiphenyl diselenide 2 is described. The method consists of the reductive cleavage of the Se-CN linkage in the corresponding aryl selenocyanates by sodium borohydride followed by air oxidation of the resulting seleno-lates. The diselenides 1 and 2 are readily obtained in a state of high purity, in 89 and 80% yield, respectively.

Regioselective Spirostan E-Ring Opening for the Synthesis of Dihydropyran Steroidal Frameworks

The regioselective opening of the ring E in spirostan sapogenins provides new dihydropyran derivatives. This novel side chain is obtained after a Lewis acid mediated acetolysis followed by an alkaline workup. The reaction mechanism is analyzed via density functional theory computations, and both experimental and computational data support the formation of an oxacarbenium intermediate. The behavior of the title skeletons under acidic conditions is also investigated.