[
I'm not a chemist, nor am I an expert on the science of acetildenafil and its related compounds. Fact checking is advisable herein.]
There is an impressive array of known research chemicals related to Viagra (sildenafil)—acetildenafil being one of which; I mention sildenafil because it's easily the least obscure of the bunch, and is practically the quintessence or beau ideal of the family.
These compounds are in a family of drugs that behave as inhibitors of the enzyme phosphodiesterase 5 (PDE5). While some are available on the market, the preponderance of these compounds aren't terribly likely to be acquired outside a research laboratory.
Apart from the drugs already mentioned here, some other sildenafil cognates, amongst a sizeable set of others, are:
Tadalafil
Vardenafil
Avanafil
Buflomedil
Trapidil
Mirodenafil
UK357903
While we know Wikipedia has its issues with reliability, I think it still can afford the layman with an adequate, albeit fragmentary and inexact, précis on technical, recondite subjects—the science behind the mechanisms of action, design, and chemistry of PDE5 inhibitors in this particular case.
Some preliminary reading material I'd think to be pertinent enough to broach (insofar as the chemistry of these drugs is your fascination) are thus:
1.)
http://en.wikipedia.org/wiki/PDE5_drug_design
2.)
[url]http://en.wikipedia.org/wiki/Phosphodiesterase_inhibitor#PDE5_selective_inhibitors [/url]
3.)
http://en.wikipedia.org/wiki/CGMP-specific_phosphodiesterase_type_5
4.)
http://en.wikipedia.org/wiki/Phosphodiesterase
Concerning the synthesis of sildenafil and its analogs, specifically:
http://www.ch.ic.ac.uk/local/projects/p_hazel/synthesis2.html
http://www.ncbi.nlm.nih.gov/pubmed/15789547
I should mention that these drugs—PDE5 inhibitors—are not as "facile" to synthesise as some of the available resources (especially that latter Pubmed reference) could easily lead the verdant, wholly unconversant chemistry dilettante toward erroneously believing.