The search terms to use on Google are contract and synthesis. I have no personal experience with any, regarding confidentiality, but I am sure most service providers in this field have off-the-shelf contracts for that. One company I know, as it was a spin-off of my alma mater: MercaChem.

From a bioinformatics point of view, it would be a more interesting question to see how you find find such service providers given the chemistry you are looking at. For example, based on similarity of building blocks they sell, compared to your drug. Or, if the company is familiar with the drug targets you have been working with. However, I am not aware of such web sites.