Development of Reactions of 6- and 5-Substituted 1,3-Dimethyluracils with Dimethylsulfoxonium Methylide
摘要:
6-Chloro-1,3-dimethyluracil (1) reacts with dimethylsulfoxonium methylide (3, 2 equiv) to give sulfoxonium ylide 8 (51%). The structure of 8 is established spectroscopically and by its reactions with various electrophiles and electron-deficient olefins. Thus, 8 is converted by HCl to sulfoxonium chloride ?, which then yields the 6-(chloromethyl)uracil 17 by heating in acetonitrile. Ylide 8 undergoes deuterium exchange at the Ei-position, at its methine carbon, and into its methyl groups attached to sulfur. Reaction of 8 with benzoyl chloride gives the highly substituted ylide 19 or the nucleophilic substitution products 17 and 18 depending on reaction conditions. Treatment of 8 with electron-deficient olefins yields 6-cyclopropyluracils 20-31. Many of the cyclopropyluracils have been converted to trans-1-(1,3-dimethyluracilyl)-2-vinylcylopropanes and cycloheptenyluracils. Reactions of 5-substituted uracils 2 (Z = SOPh and SeOPh) with ylide 3 have been developed. 5-(Phenylsulfinyl)uracil 48 yields cyclothymine derivative 49; 5-phenylseleninyluracil 52 gives methylide 8 as the major product.
Synthesis of substituted uracils by the reactions of halouracils with selenium, sulfur, oxygen and nitrogen nucleophiles under focused microwave irradiation
Undermicrowaveirradiation, the nucleophilic substitutionreactions of halouracils with selenium, sulfur, oxygen and nitrogen nucleophiles was complete within several minutes with yields up to 99%. The method using microwaveirradiation is superior to those conducted under conventional heating processes.
Palladium-Catalyzed Carbon−Sulfur Cross-Coupling Reactions with Indium Tri(organothiolate) and Its Application to Sequential One-Pot Processes
作者:Jae-Young Lee、Phil Ho Lee
DOI:10.1021/jo801169h
日期:2008.9.19
tri(organothiolate) is an effective nucleophilic coupling partner in Pd-catalyzedC-Scross-coupling reactions to produce the functionalized sulfides in excellent yields with high atom efficiency and complete regio- and chemoselectivity. The present method was efficiently applied to the sequential one-pot processes composed of selective double C-Scross-coupling reactions and addition of allylindium or allenylindium
Copper-Catalyzed Regioselective Direct C-H Thiolation and Thiocyanation of Uracils
作者:Medena Noikham、Sirilata Yotphan
DOI:10.1002/ejoc.201900343
日期:2019.4.30
The copper‐catalyzed directC–H thiolation and thiocyanation of uracils using disulfides and thiocyanate salts respectively as coupling partners have been successfully developed. These protocols enable the C–H bond cleavage and C–S bond formation to proceed efficiently, providing useful methods to access of a diverse array of thio‐substituted at the 5 position of uracil derivatives in good to excellent
resulting C-5 lithiated species with various types of electrophiles furnish 5-substituted 6-phenylthiouridine derivatives. The phenylthio group in these products can be removed by a new type of desulfurizative stannylation with tributyltin hydride followed by protonolysis. The whole sequence constitutes a newroute to 5-substituted uridines. Application of this method to 2'-deoxyuridine is also described