Beilstein J. Org. Chem.2021,17, 2629–2641, doi:10.3762/bjoc.17.176
-nitrothioacetates in good yields and enantioselectivities [27]. A sulfinylurea catalyst was also applied to catalyze the addition of 3-substituted pyrazol-5-ones to trisubstituted nitroalkenes. The adducts were obtained with good yields and enantioselectivities up to 91:9 er [28].
Inspired by the previous
Beilstein J. Org. Chem.2018,14, 2589–2596, doi:10.3762/bjoc.14.236
10.3762/bjoc.14.236 Abstract Multistep syntheses of novel 17β-pyrazol-5'-ones in the Δ5-androstane series were efficiently carried out from pregnenolone acetate. A steroidal 17-carboxylic acid was first synthesized as a norpregnene precursor by the bromoform reaction and subsequent acetylation. Its CDI
the reference compound, cisplatin.
Keywords: antiproliferative activity; Knorr reaction; microwave; pyrazol-5-ones; steroids; Introduction
17-exo-Heterocyclic androstanes with five or six-membered heterocyclic rings connected directly to C-17 of the sterane core represent a remarkable subclass of
as the necessity of high temperature or prolonged reaction time and low yields of the desired products [14]. A rate acceleration and yield improvement could be achieved in some cases by performing the reactions under microwave (MW) conditions [15][16][17]. Especially with respect to pyrazol-5-ones
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Graphical Abstract
Scheme 1:
Multistep synthesis of steroidal β-ketoesters 4 and 4' from pregnenolone acetate (1) and pregnadien...