## Results and Discussion  
### Synthetic Studies  
For the synthesis of D-ring-fused 5-aminopyrazoles, DHEA was used as a starting material. Formylation at C-16 with ethyl formate in the presence of a strong base by the Claisen condensation and the following acidification led to compound **1**[27], which can exist as equilibrating tautomers (**1a-c**) in solution (Scheme 1). The predominance of one or the other forms is highly affected by the priority and polarity of the solvent; however, **1b--**where enolization occurs on the formyl group--was found to prevail in neutral organic medium based on NMR measurements [28]. Condensation reaction of **1** with hydroxylamine hydrochloride in EtOH in the presence of NaOAc resulted in the corresponding oxime capable of ring-chain tautomerism. Thus, two additional cyclic tautomers (**2d** and **2e**) can contribute to the equilibrium besides the three open forms (**2a-c**) [29]. According to \({}^{1}\)H and \({}^{13}\)C NMR (J-MOD) measurements, only one of the possible tautomers (**2d**) is present in dimethyl sulfoxide (DMSO) solution in good agreement with previous studies, where the same form was evidenced by IR and XRD in the solid-state [23]. **Scheme 1. ** Multistep synthesis of a steroidal \(\beta\)-ketonitrile (**3**) from dehydroepiandrosterone (DHEA) reagents and conditions: (**i**) HCOOEt, NaOEt, CH\({}_{2}\)Cl\({}_{2}\), rt., 5 h; (**ii**) NH\({}_{2}\)OH-HCl, NaOAc, EtOH, reflux, 1 h; (**iii**) KOH, MeOH, rt, 30 min. Treatment of 2 with KOH in MeOH at room temperature or below resulted in a \(\beta\)-ketonitrile (3) as a mixture of two epimers in excellent yield via base-induced elimination of a water molecule (Scheme 1). It is important to note, however, that (_a_,1_,_a_)-type fragmentation can occur leading to a D-seco-carboxylic acid (4) at higher temperatures or by using a stronger and/or excess base [30]. The \({}^{1}\)H NMR spectrum of compound **3** showed some duplicated proton peaks (16-H, 18-CH\({}_{3}\)) at different chemical shifts and with different integrals, indicating the presence of two diastereomers in a ratio of about 2:1. Furthermore, the peak shapes of the 16-H protons allowed us to identify the epimers; that is, a triplet at 3.78 ppm (\(J\) = 9.3 Hz) was assigned for the 16\(\beta\)-CN derivative, while a doublet at 4.36 ppm (\(J\) = 8.7 Hz) was assigned for the 16\(\alpha\)-CN isomer. The splitting and coupling constants of 16-H signals corresponded to the dihedral torsion angles 0(H16,C16,C15,H15\(\alpha\)) and 0(H16,C16,C15,H15\(\beta\)) calculated based on the Karplus equation for the two stereoisomers of **3**. In the following, \(\beta\)-ketoester (**3**) was used for the synthesis of steroidal heteroaromatic 5-aminopyranoside without separating the diastereomers, since the asymmetric center disappears during the ring-closure step with arylhydrazines. For preliminary experiments, compound 3 and phenylhydrazine hydrochloride (**5a**, 1.2 equiv.) were reacted in EtOH under MW irradiation at different temperatures (80, 100, and 120 \({}^{\circ}\)C) for 5, 10, 15, and 20 min in a closed vessel and the progress of the transformations was monitored by thin-layer chromatography (TLC). Of all the reaction conditions, 120 \({}^{\circ}\)C and 10 min were found to be optimal for the complete conversion of the starting material. However, alkaline work-up was needed in this case to neutralize the reaction mixture; otherwise, a certain amount of the desired product was lost with the aqueous phase due to its basic characteristic of forming a HCl salt in the presence of an excess reagent. Alternatively, the MW-assisted transformation could also have been carried out within 10 min in the presence of NaOAc (1.2 equivalent) to liberate the binc nucleophilic reagent from its HCl salt, and the product (**6a**) was again obtained in excellent yield after purification by column chromatography (Table 1, entry 1). The reaction of 3 with **5a** was also performed in refluxing EtOH for comparison.