I'm guessing that you (like me) come from one of exactly 7 countries whose citizens have the privilege of being able to apply for a work visa from within Germany while here on a tourist visa (or, more commonly, a visa-waiver). I can assure you that Syria is most definitely not on that list, and that almost everyone in the world is actually required to obtain a work visa in their home country.
I am. My girlfriend is not. We both got our visas in Germany. (Her case, however, was slightly different than the norm since she went from an academic work visa for post-docs, to a Blue Card, to permanent residence.)
A Syrian would certainly need a visa to enter Germany in general. I believe that you're incorrect as to whether or not, given a valid visa to enter the country, a Syrian citizen would be able to apply for a further visa from within the country.
For reference, this is the actual law that I was referring to which provides for highly qualified foreigners to get a visa to look for work in Germany for six months:
I believe the only point in question is if a Syrian would be able to apply for that from within Germany with a valid visitors' visa, or if they'd need to apply for that from outside of Germany.
I believe zb is correct. I'm also a Blue Card holder living in Berlin, and as a US citizen, I was able to enter Germany on a tourist visa and then apply for the Blue Card from here. However, a friend of mine from the Philippines was in a very similar situation (got a job offer while he was here on a tourist visa) and he had to return home to apply for the Blue Card, since the Philippines are not on that short list of exempted countries. Your girlfriend's case was indeed different, since she wasn't trying to convert from a tourist visa.
Starting around "Important! If you enter the country without a visa or with a Schengen visa..." (This site's aimed towards students, but I believe the info on entering the country is still applicable here.)
In the OP's specific case (especially considering the fact that the German embassy in Syria is currently closed), I would definitely recommend contacting an immigration lawyer in Germany before entering the country. It's possible that there are other options or exceptions that I'm not aware of.
EDIT: Just noticed that those two links have slightly different lists of exempted countries. The daad.de link might just be out of date, because the following official site also lists only seven countries: http://www.berlin.de/labo/auslaender/dienstleistungen/bes_st...
