Studies on organophosphorus compounds—XL

[2 + 3]‐Cycloadditions of Phosphonodithioformate S‐Methanides with CS, NN, and CC Dipolarophiles

“…9H-Fluorene-9-thione (thiofluorenone) (12a) was prepared by treatment of 9H-fluoren-9-one in EtOH soln. either with a mixed stream of H 2 S and HCl [20] or by heating with Lawesson's reagent in boiling toluene [21].…”

Synthesis and optoelectronic properties of chemically modified bi-fluorenylidenes

“…4 Due to the almost infinite synthetic versatility and the high potential in molecular design, precise control of the photophysical and electrochemical properties may be achieved by the modification of the chromophore skeleton or the introduction of substituents. 5 Hence, a whole arsenal of molecular structures of organic dye sensitizers for DSSCs is present in the literature, and the information about the relationship between the chemical structure of the dyes and their photovoltaic performances in DSSCs is steadily increasing. In fact, families of organic dyes, which exhibit high DSSC performances, such as polyenes, hemicyanines, thiophene-based dyes, coumarins, indolines, heteropolycyclic dyes, boron dipyrromethenes (BODIPYs), merocyanines, xanthenes, perylenes, carbazoles, porphyrins, catechols, polymeric dyes, squaraines, cyanines and phthalocyanines (Pcs) have been reported.…”

Lawesson’s Reagent: Endowed With Wide Utility in Organic Synthesis

“…(B) Moulin and co-workers 6 showed that LR is an excellent promoter for heterocyclization of a variety of acetohydrazidepyridines to the corresponding [1,2,4]triazolo [4,3-a]pyridines in high yields. …”

“…However, this reagent can efficiently be applied to many other reactions, in particular for the deoxygenation of heterocyclic halobenzyl alcohols, 5 to heterocyclization of acetohydrazidepyridines, which yields [1,2,4]triazolo [4,3-a]pyridines, 6 to afford pyrazoles, 7 to [4+2] cycloaddition of a,b-unsaturated ketones, 8 and as a racemization-free coupling reagent in peptide synthesis. 9 LR is stable in solvents like toluene, THF, dichloromethane, and pyridine, 10 it can be used under microwave irradiation and for automated parallel synthesis; it is commercially available and easily prepared by reaction of P 4 S 10 with anisole under heating.…”

“…Lawesson's Reagent (LR, Figure 1), 2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphethane-2,4-disulfide is a versatile and effective thionation reagent; 1 it is best known for the conversion of a wide variety of carbonyl into thiocarbonyl compounds, including the synthesis of phosphorus-and sulfur-containing heterocycles, such as thiazolidinediones, 2 thiothalidomides, 3 2H-benzo [1,4]thiazine, 4 among others. However, this reagent can efficiently be applied to many other reactions, in particular for the deoxygenation of heterocyclic halobenzyl alcohols, 5 to heterocyclization of acetohydrazidepyridines, which yields [1,2,4]triazolo [4,3-a]pyridines, 6 to afford pyrazoles, 7 to [4+2] cycloaddition of a,b-unsaturated ketones, 8 and as a racemization-free coupling reagent in peptide synthesis.…”