protocol for the preparation of hetaryl and ferrocenyl functionalized thioketones via treatment of the corresponding ketones with Lawesson's reagent (L.R.) under microwave irradiation (M.W.). The application of microwaves reduces the reaction time and in most cases leads to the improvement of yields of isolated, pure thioketones.
Synthesis of ferrocenyl- and hetaryl-substituted 2,2,2-trifluoroethanols and their conversion into 2,2,2-trifluoroethanethiols using Lawesson’s reagent
with the Ruppert-Prakash reagent and, after desilylation of the intermediate adduct, gave the corresponding tertiary 2,2,2-trifluoroethanols. Similarly, ferrocenyl carbaldehyde was converted into 1-ferrocenyl-2,2,2-trifluoroethanol via nucleophilic trifluoromethylation. Some of the obtained fluorinated alcohols were transformed into thiols by treatment with Lawesson’s reagent or P2S5·2C5H5N complex.
二茂铁基和杂芳基取代的酮与Ruppert-Prakash试剂平稳反应,并且在中间加合物甲硅烷基化后,得到相应的叔2,2,2-三氟乙醇。类似地,二茂铁基甲醛通过亲核三氟甲基化转化为1-二茂铁基-2,2,2-三氟乙醇。通过使用Lawesson试剂或P 2 S 5 ·2C 5 H 5 N络合物处理,将所得的某些氟化醇转化为硫醇。显着地,所获得的硫醇是无味的化合物。
Trifluoromethylated 2,3-dihydro-1,3,4-thiadiazoles via the regioselective [3+2]-cycloadditions of fluorinated nitrile imines with aryl, hetaryl, and ferrocenyl thioketones
A series of hydrazonoyl bromidespreparedfromreadily available N-arylhydrazones of fluoral was used for the in situ generation of fluorinated nitrile imines. These 1,3-dipoles were efficiently trapped with aryl and hetaryl thioketones yielding fluoromethylated 2,3-dihydro-1,3,4-thiadiazoles. The [3+2]-cycloadditions occurred with complete regioselectivity yielding the respective products in high
由易得的氟代N-芳基azo酮制备的一系列酰溴用于原位生成氟化腈亚胺。这些1,3-偶极有效地被芳基和杂芳基硫酮捕获,生成氟甲基化的2,3-二氢-1,3,4-噻二唑。[3 + 2]-环加成反应具有完全的区域选择性,从而以高收率产生了相应的产物。反应具有显着的耐受性进行到官能团,以及相应的Ñ(3)轴承卤素,甲氧基,苯甲酰氧基,甲氧羰基,和取代基腈在芳基衍生物对苯基环的位置被制备为结晶性产物。光谱数据(13 C和所获得的[3 + 2]-环加合物的19 F NMR)表明CF 3基团的屏蔽效应与对位取代基的电子性质之间存在显着的关系。
Palladium‐Catalyzed Direct Cross‐Dehydrogenative Alkynylation of Selenophenes
A palladium-catalyzed (Pd(PPh3)4/Ag2O/PivOH) C2-regioselective direct dehydrogenative alkynylation of unsubstituted selenophene was achieved. The selenophenes substituted with R1 groups at 2-position can be C5-alkynylated with a variety of 4-substituted phenylacetylenes (R2 groups). The R1 and R2 can be either electron-withdrawing or electron-donating groups, demonstrating a wide range of substrate
lithiated heterocycles. Under typical conditions, selected examples of the hetaryl thioketones were oxidized selectively to give thiocarbonyl S-oxides (sulfines). Reactions with diazomethane at –65°C yielded 1,3-dithiolanes in a regioselective manner and hetero-Diels–Alder reactions of 2-thienyl substituted thioketones with dimethyl acetylenedicarboxylate yielded the corresponding 7H-thieno[2,3- c]thiopyran-4