Steroide. LXX [1]. Stereoselektive Epoxidation von 14,15‐ungesättigten Östratrien‐3‐methylethern. Zum syn‐dirigierenden Effekt von Urethanen

Abstract

Steroides. LXX. Stereoselective Epoxidation of 14,15‐Unsaturated Estratriene‐3‐methyl Ethers. On the syn‐Directive Effect of Urethanes The stereochemistry of the epoxidation of 14,15‐unsaturated estratriene‐3‐methyl ethers with peroxyacids is examined. The influence of different 17‐substituents and of the solvent on the stereoselectivity is discussed. Whereas on epoxidation of 17β‐esters and 17β‐ethers mainly 14α, 15α‐epoxides are formed (up to 89%), the 17β‐urethane derivatives yield the 14β, 15β‐epoxides up to 87% by a syn‐directive effect.

Palladium‐Catalyzed Stereoselective Intramolecular Oxidative Amidation of Alkenes in the Synthesis of 1,3‐ and 1,4‐Amino Alcohols and 1,3‐Diamines

“…The latter product was then oxidized with m-CPBA in CH 2 Cl 2 to furnish epoxide 23 (68 %) as a 7:1 mixture of diastereoisomers. [21][22][23] Subsequent cyclization was carried out in the presence of BF 3 ·Et 2 O (10 mol %), and afforded the desired pure diastereoisomer 24 (68 %). Scheme 5.…”