Microwave assisted preparation of C(1)–C(11) oxygen-bridged pregnanes

• Published in: Steroids Vol. 76; no. 13; pp. 1458 - 1464
• Main Authors: Alvarez, Lautaro D., Sonego, Juan M., Veleiro, Adriana S., Burton, Gerardo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Inc 11-12-2011; Elsevier
• Subjects: 1,11-Epoxypregnane; Biological and medical sciences; Diacetoxyiodobenzene; Fundamental and applied biological sciences. Psychology; Microwave irradiation; Remote functionalization; Vertebrates: endocrinology; Diacetoxyiodobenzene; Remote functionalization; Microwave irradiation; 1,11-Epoxypregnane; Microwave; Oxygen
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2011.07.016

► Microwave irradiation induces hypoiodite type reactions with DIB/iodine. ► On sensitive substrates, photolysis with visible light is advantageously replaced by microwaves. ► Using microwave irradiation the 1α,11α-epoxy-4-pregnene was obtained in good yield. ► The stereochemical outcome of 1,11-bridge formation is explained by molecular modeling.
1,11-Epoxysteroids may be obtained by an intramolecular remote functionalization using Suarez reagent (diacetoxyiodobenzene/I
2) and irradiation with visible light. We have found that photolysis with visible light may be advantageously replaced by microwave irradiation to prepare 1,11-oxygen bridges resulting in higher yields and shorter reaction times especially in the case of sensitive substrates. Both methodologies were compared on a set of representative 11-α-hydroxypregnanes (
3,
8,
10 and
11).