All classes of hydroxyl groups are converted to TMS ethers, including moderately hindered and unhindered hydroxyl groups
Tri-Sil TBT is a powerful catalyzed silylation reagent formulation that contains a 3:3:2 mixture of trimethylsilylimidazole (TMSI), N,O-bis-(trimethylsilyl)acetamide (BSA) and trimethylchlorosilane (TMCS). This reagent enables conversion of hydroxyls to trimethylsilyl derivatives. With proper selection of silylation reagents, unhindered, moderately-hindered and highly-hindered hydroxyls may be selectively silylated. BSA alone will silylate the unhindered 3a, 20a, and 21 hydroxyl groups on cortol (5b-pregnane-3a, 11ß, 17, 20a, 21-pentol); BSA with TMCS will silylate the aforementioned hydroxyls plus the moderately hindered 11b hydroxyl; and Tri-Sil TBT will silylate all five hydroxyls, including the highly-hindered 17a hydroxyl.
Note: When using a Tri-Sil TBT/dimethylformamide mixture, discard mixture after 12 hours.
References
1.Seidel, V., et al. (1993). Chromatographia 37: 191-201. 2.Mollica, J. A. and Strusz, R. F. (2006). Analysis of corticosteroid creams and ointments by high pressure liquid chromatography. J. Pharma. Sci 61(3): 444-47. 3.Saisho, K., et. al. (2001). Hair Analysis for Pharmaceutical Drugs. II. Effective Extraction and Determination of Sildenafil and Its N-Desmethyl Metabolite in Rat and Human Hair by GC-MS. Biol. Pharm. Bull. 24(12): 1384—1388. 4.Serdar, B., et. al. (2003). Urinary Biomarkers of Exposure to Jet Fuel (JP-8). Environ. Health Persp. 111: 1760-64.
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