This paper describes the facile synthesis of sildenafil citrate (1) and its related compounds through an improved chlorosulfonation reaction using chlorosulfonic acid and thionyl chloride. This synthesis results in pure sildenafil with high yield. The structures of the compounds were determined with infrared (IR), ¹H-NMR and 13C-NMR spectroscopic methods, and high resolution mass spectroscopy (...

Reaction of thionyl chloride with 7-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4- oxoquinoline-3-carboxylic acid 1 gave acid chloride 2. Compound 2 was reacted with glycine and D-glutamic acid to afford 2-(7-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,4- dihydroquinoline-3-carbonyl) aminopantandioicacid 3a and 2-(7-chloro-1-cyclopropyl-6- fluoro -4- oxo-1,4-dihydroquinoline-3-carbonyl)aminoacetica...

Efficient cleavage of sterically hindered boronic esters of asymmetric diols to recover both the diol and a more reactive borane derivative has been a challenging problem. A remarkable borosilicate glass-catalyzed cleavage with thionyl chloride and imidazole proved less useful than hoped for. Potassium bifluoride converts boronic esters to diols and alkyltrifluoroborates. These with chlorosilan...