Investigations on photochemical linking of steroids with amino acids: Irradiation of α, β-unsaturated steroidal ketones in the presence of amino acids in aqueous medium

Abstract

<span style="font-size:12.0pt;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">Irradiation of 1, 4-cholestadien-3-one 1 in THF-H₂O solvent in the presence of amino acids (glycine/alanine) leads to dienone-phenol photo rearrangement products, 3-hydroxy-l-methyl-19-norcholesta-1, 3, 5 (10) -triene <b style="mso-bidi-font-weight:normal">3</b> (35%), 4-hydroxy- 2-methyl-19-nor-cholesta-1, 3, 5 (10) -triene <b style="mso-bidi-font-weight: normal">4</b> (15%), 1-hydroxy-4-methyl-19-norcholesta-1, 3, <b style="mso-bidi-font-weight:normal">5</b> (10)-triene <b style="mso-bidi-font-weight: normal">5</b> (28%) along with a novel methyl substituted-19-norcholesta-1, 3, 5 (10)-triene <b style="mso-bidi-font-weight:normal">6</b> and a spirocyclic-enone <b style="mso-bidi-font-weight:normal">7</b>; no amino acid or solvent addition product is obtained. Irradiation of 16-dehydropregnenolone-3β-acetate <b style="mso-bidi-font-weight:normal">2</b> under identical conditions in the presence of glycine affords the pregnenolone-3β -acetate <b style="mso-bidi-font-weight: normal">9</b> (25%), 16-(tetrahydrofuran-2-yl) -pregnenolone-3β-acetate <b style="mso-bidi-font-weight:normal">10</b> and its 17- α-isomer <b style="mso-bidi-font-weight:normal">11</b> (together 35%) and 16-(glycin-2-yl) -pregnenolone-3β-acetate <b style="mso-bidi-font-weight:normal">12</b> (mixture of isomers, 25%). The results are compared and contrasted with known photochemical behaviour of steroidal enones and dienones. The studies indicate that steroidal-16-ene-20-ones can be better photoaffinity labelling agents for progestogen and possibly, adrenal steroidal receptors. Also, the photochemical additions to ∆¹⁶-20-one steroidal systems can be exploited for the introduction of substituents/moieties at C₁₆ in steroids.</span>