Steroids, XLI. Neighbouring Group Participation, X. Neighbouring Group Participation and Fragmentation During the Solvolysis of the Epimers of 3‐Methoxy‐16‐(tolylsulfonyloxymethyl)‐estra‐1,3,5(10)‐trien‐17‐ol

Abstract

The four possible isomers of 16‐hydroxymethyl‐3‐methoxyestra‐1,3,5(10)‐trien‐17‐ol were converted into the 16‐tolylsulfonyloxymethyl‐17‐acetoxy esters 1b, 3b, 4b, 7b and into the 16‐tolylsulfonyloxymethyl‐17‐tetrahydropyranyl acetals 1c, 3c, 4c, 7c. On alkaline methanolysis of 1b and 7b, the α and β oxetanes 2 and 8 condensed to the D ring in the sterane skeleton were formed, while 3b and 4b yielded the fragmented product 5. Under similar experimental conditions, the acetals 1c, 3c, 4c, 7c were transformed into the 16‐methoxymethyl derivatives 1d, 3d, 4d, 7d.

Synthesis of Novel D‐Secoestrone Isoquinuclidines by an Unpredicted Iminium Ion‐Induced 1,5‐Hydride Shift

“…Reaction of the secoestrone aldehyde 2a derived from 3-methoxyestrone (1a) and p-bromoaniline in the presence of BF 3 ·OEt 2 as a key step, [30] was hydrogenated to give the saturated aldehyde 6a (Scheme 2). Treatment of 6a with aniline (7) or with its mono-, di-and trisubstituted derivatives 8Ϫ28, containing electron-withdrawing halo, nitro or halomethyl groups in different positions, produced the imines 29Ϫ50, which readily underwent transformation in the presence of BF 3 ·OEt 2 .…”

Heterogeneous Catalytic Enantioselective Hydrogenation of Activated Ketones

“…Studies on enantioselective catalytic hydrogenation at the University of Szeged started with the investigation of the MRNi catalyst [247][248][249][250]. These studies were also extended to the hydrogenation of steroids [251][252][253][254][255][256][257][258], an important family of compounds successfully researched at the University of Szeged [259][260][261][262]. Finally, last year a new project was launched to study the enantio-and diastereoselective hydrogenation of certain other compounds containing prochiral C=C bonds [263][264][265].…”

Synthesis of Unusual Bridged Steroid Alkaloids by an Iminium Ion Induced 1,5-Shift of a Benzylic Hydride

“…Recently, we have developed the synthesis of dhomosteroid 5 by a domino Knoevenagel hetero Diels ± Alder reaction [2] of Meldrums acid 4 and the steroid derivative 2 a, [3] which was obtained from estrone 3-methyl ether 1 in four steps. [4] In this sequence a 1-oxa-1,3-butadiene is formed as an intermediate.…”