Photochemical and Beckmann rearrangement of (Z)-cholest-4-en-6-one oxime

Abstract

Beckmann rearrangement of (Z)-cholest-4-en-6-one oxime (4) (prepared in 4 steps starting from cholest-5-en-3?-ol ?1)) with thionyl chloride in dioxane solution afforded an enamide-type lactam, i.e. 7-aza-B-homocholest-4-en-6-one (6) as a single product. Photoreaction of the same compound in methanol or benzene-acetic acid solution gave a mixture of products, with the formation of the parent ketone 3 and the occurrence of Z/E isomerization, while the lactam 6 was obtained only when the reaction was performed in methanol and then in very low yield (7%).

Thionation of Some α,β-Unsaturated Steroidal Ketones

“…Recently we reported synthesis of 6-thioxo-7-aza-B-homocholest-4-ene and 6-aza-7-thioxo-B-homocholest-4-ene using Lawesson’s reagent [1]. Continuing this investigation and our previous work on modified steroid compounds as biologically active molecules [1,2,3,4], the goal of this study was to synthesize some new thioxosteroid derivatives.…”

Synthesis of New Drimane and Homodrimane Lactams by Beckmann Rearrangement of Some Ketoximes

“…The NOESY correlations between H-12 and H 3 -16, as well as H-12 and H-11, demonstrate the trans nature of the isomer at  5 (12) . The NOESY correlation between H-4 and H-7 indicates that they are in the α-plane and determines the (R) relative confi guration at C-4 ( Figure 4).…”

“…The treatment of ketoxime 22 with thionyl chloride in anhydrous dioxane according to the literature procedure [9,12] 13 C HSQC NMR spectra suggested the presence of three isolated spin systems: CH 2 CH 2 CH 2 (C-11 to C-9), CHCH 2 NH (C-7 to NH), and CHCH 3 (C-4 to C-13) (Figure 3 The migration of a double bond  4(5) in precursor 23 to  5 (12) , as a result of the reaction, has additionally generated two centres of isomerism: a geometrical centre at C-5/C-12 and an optical one at C-4. The NOESY correlations between H-12 and H 3 -16, as well as H-12 and H-11, demonstrate the trans nature of the isomer at  5 (12) .…”

Man-Made Cytotoxic Steroids: Exemplary Agents for Cancer Therapy

“…Despite the presence of a 4,5 double bond, the E-isomer 76 induced high cytotoxicity in the form of apoptosis in targeted tumor sensitive cell line (IC 50 = 20.68 ± 3.10 and 11.16 ± 1.24 μM against HeLa and K-562 cell lines, respectively) and the low toxicity without apoptotic events in isolated peripheral blood mononuclear cells from normal human volunteers in vitro. 169,170 O-Alkylated derivatives of various oxime precursors, in which oxime functionality is placed at various positions of steroidal skeleton, have been synthesized and evaluated for their cytotoxic activity by Jindal et al 171 Compounds 77 and 78 (Figure 14) were found to be most active ones in the in vitro assay against 60 human tumor cell lines and were further screened for preliminary in vivo hollow fiber assay. 171…”