Chlorination of 20-Oxopregnanes with the Manganese Dioxide–Chlorotrimethylsilane/Acetyl Chloride System: A Simple Approach Towards the Construction of the Corticosteroid Side Chain

Abstract

C-21 chlorination of 20-oxosteroids using the system MnO 2 (excess)±TMSCl or MnO 2 (excess)±AcCl in acetic acid medium as well as an example of a Wagner±Meerwein rearrangement of 17-chloro-20-oxopregna-3-yl acetate to 17--methyl-18-nor-17-pregn-13-en-3-yl acetate have been demonstrated.

Synthesis of some novel steroidal 1,2,4,5-tetraoxanes

“…The product was characterized by direct comparison with the authentic materials. 26,28,29 This compound 3 was reacted with alkaline methanolic solution to give the 3b-hydroxy Favorskii rearrangement product 4. 30,31 Catalytic hydrogenation of 4 in the presence of Pd/C provided the hydrogenated compound 5 in high yield.…”

Bismuth(III) triflate-catalyzed rearrangement of 16α,17α-epoxy-20-oxosteroids. Synthesis and structural elucidation of new 16α-substituted 17α-alkyl-17β-methyl-Δ13-18-norsteroids

“…17 On the other hand, treatment of 17a-choro-20-oxo-5a-pregnan-3b-yl acetate with anhydrous NaOAc in glacial AcOH, afforded the corresponding 17b-methyl-D 13 -18-norsteroid in good yield. 18 Quite recently, Iglesias-Arteaga et al reported the use of the BF 3 $Et 2 O/Ac 2 O system in the synthesis of polyhydroxylated 17a,17b-dialkyl-D 13 -18-norsteroids by regioselective cleavage of furostanols derived from diosgenin and sarsasapogenin. 19 The Wagner-Meerwein-type rearrangement of 16a,17a-epoxysteroids has been reported to afford 17b-methyl-D 13 -18-norsteroids bearing an O-containing function at C16, which constitutes an important synthetic advantage.…”

Functionalisation at the C-16 Position of 16-Dehydro-20-Oxopregnanes (Steroid Drug Intermediates) via Vinyl Nitration with CAN–NaNO2–CH3CN System

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Functionalisation of steroidal molecules at different strategic positions is an important area of research in the development of modified steroids possessing diverse biological properties including anti-tumour activity. 1 In continuation of our work on steroids [2][3][4] and in an effort to form a steroid analogue of nitrocyclopentane carboxylic acid (ANCPA), 5 we studied the reaction of 16-dehydro-20-oxopregnanes 1-3 which are available in our laboratory [2][3][4] with the CAN-NaNO 2 -CH 3 CN system to effect the nitroacetamidation reaction 6 on the double bond of the α,β-unsaturated ketone at the C-16, C-17 -position. However, when compounds 1-3 were treated with the reagent by heating at 50°C, all furnished exclusively vinyl nitro derivatives, viz, ∆ 16 -16-nitro-20-oxo pregnane 4, ∆ 5,16 -16-nitro-20oxopregnane 5 and ∆ 16 -16-nitro-21-chloro-20-oxopregnane 6 respectively, in excellent yield.

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