9/6/2023 0 Comments Nitro pdf professional 5.2.0.5![]() ![]() Most of these methods are efficient only for electron-rich pyridyl ITCs, because electron-deficient aminopyridines lack enough reactivity to form dithiocarbamate salts, which results in low yield or excess (hundredfold) use of carbon disulfide. Although some desulfurylating reagents for this approach were developed, the first step, preparing the N-pyridyldithiocarbamate salts, was often neglected. The intermediate dithiocarbamate salts are generated by treatment of amines with carbon disulfide and Et 3N. Another two-step approach, based on reagent-promoted decomposition of dithiocarbamate salts into ITCs, was first reported by Le Count in 1977. The high toxicity and incompatability of thiophosgene with many functional groups limit its general use, furthermore, these ‘thiocarbonyl transfer’ reagents are not readily available and often do not work as desired due to the formation of thiourea byproducts. The most well-known method is based on thiophosgene, and later refinements of ‘thiocarbonyl transfer’ reagents such as thiocarbonyl-diimidazole and dipyridyl-thionocarbonate. ![]() There are two main methods to convert substituted aminopyridines into the corresponding ITC analogue ( Scheme 1).
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