• to copy, distribute, display, and perform the work.• to make derivative works. Under the following conditions:• Attribution -You must give the original author credit.• Non-Commercial -You may not use this work for commercial purposes.• Share Alike -If you alter, transform, or build upon this work, you may distribute the resulting work only under a licence identical to this one. For any reuse or distribution, you must make clear to others the licence terms of this work. Any of these conditions can be waived if you get permission from the author. Your fair use and other rights are in no way affected by the above. The synthetic feasibility of any compound library used for virtual screening is critical to the drug discovery process. TIN, a recursive acronym for "TIN Is Not commercial", is a virtual combinatorial database enumeration of diversity-orientated multicomponent syntheses (MCR). Using a "one-pot" synthetic technique, 12 unique small molecule scaffolds were developed, predominantly styrylisoxazoles and bis-acetylenic ketones, with extensive derivatization potential. Importantly, the scaffolds were accessible in a single operation from commercially available sources containing R-groups which were then linked combinatorially. This resulted in a combinatorial database of over 28 million product structures, each of which is synthetically feasible. These structures can be accessed through a free webbased 2D structure search engine, or download in SMILES, MOL2 and SDF formats. Subsets include a 10% diversity subset, a drug-like subset and a lead-like subset that are also freely available for download and virtual screening (http://mmg.rcsi.ie:8080/tin).