Sildenafil molecular structure

In 2005 we reported the synthesis of some sildenafil (3) analogues and their tyrosinase inhibitory potential [43]. The compoimds were synthesized using microwave irradiation in key steps, such as the SNAr reaction on important precursor bromopyrazole [44]. Their molecular structures are shown in Fig. 3. 

Fig. 3 Molecular structures of the synthesized sildenafil (3) and some of its analogues (4-7) which exhibited promising tyrosinase inhibitory activities [43]...

Ten reference spectra of five European Viagra tablets 50 mg (top and bottom) are shown in Figure 32.1. Small absorption bands of the active ingredient, sildenafil citrate, can be seen in the spectral range 6500 to 5500 cm (see detail view in Figure 32.1). No differences were found between the reference spectra of European and American makes. The in-between correlation is larger than 0.9980. The NIR spectrum and the molecular structure of Sildenafil citrate is presented in Figure 32.2. 

FIGURE 32.2 NIR spectrum of Sildenafil citrate and the molecular structure of Sildenafil. 

FIGURE 5.9. Molecular structures of tadalafil (Cialis is a registered trademark of Eli Lily and Company), sildenafil (Viagra is a registered trademark of Pfizer Inc.), and vardenafil (Levitra is a registered trademark of Bayer Pharmaceuticals Corp.). 

Figure 5.9. Molecular structures of tadalafil, sildenafil, and vardenafil...

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