Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• unsuccessful. However, with diazonium salts generated with tert-butyl nitrite in acetonitrile in the presence of CuSCF3 and BF3 better results were obtained [121]. Yields of the resulting aryltrifluoromethyl sulfides improved (~40–70%). The best results were observed with isolated tetrafluoroborate diazonium

• salts (Scheme 37), although the presence of electron-donating and bulky ortho-substituents in the aromatic ring led to reduced yields. 4. Perfluoroalkylation of aromatic sulfur compounds Perfluoroalkyl iodides have not generally been considered as alkylating agents. Unlike R-X they show anomalous

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• are obtained by photochemical decomposition at very low temperature of diazonium salts 19 (several synthetic steps are required to obtain such precursors including the construction of the CF3O-aryl moiety) (Scheme 15). The trifluoromethyloxonium salts decompose to yield CF4 and dibenzofuran

• -(trifluoromethoxy)biphenylyl-2′-diazonium salts such as 19a (R=H) through in situ generation of a trifluoromethyloxonium salt. The yield of trifluoromethylated products was highly dependent on the counteranion as observed in the trifluoromethylation of phenol (Scheme 17) [23]. The synthetic application of thermally

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• ][12], diazonium salts [13][14], arylsulfonyl halides [15] and aroyl chlorides [16] have also been used. Several protocols were recently described that draw on widely available carboxylic acid derivatives as alternative aryl sources. This not only extended the substrate basis of Heck reactions, but

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• ][17] (DTDAF) 6 (Scheme 1) and later by electrochemical means [18], we were keen to compare the outcomes of these reactions of diazonium salts with those arising from the use of alternative neutral organic electron donors [19][20]. An interesting member of these alternative reagents is the commercially

• achieve the easier step of reducing arenediazonium salts to aryl radicals, but not the more difficult step (aryl radicals to aryl anions). The redox potentials associated with TTF are +0.32 V and +0.71 V vs SCE [62] so, even transferring one electron to the diazonium salts would superficially appear

• 1.5 equivalents of TDAE, it afforded the unstable exocyclic alkene 50a as the sole product, which after treatment with p-toluenesulfonic acid tautomerised to the indole 51a in an overall 68% yield in three steps from 48a. Adopting the optimized procedure, the diazonium salts 49b–d on treatment with

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• . However, the difficulty in the use of these reagents is the in situ preparation by photochemical decomposition of the corresponding 2-(trifluoromethoxy)biphenylyl-2'-diazonium salts at −100 °C (Scheme 7) [28]. The major drawback of this method is the necessity to work at very low temperature and on small

An easy synthesis of 5-functionally substituted ethyl 4-amino- 1-aryl- pyrazolo- 3-carboxylates: interesting precursors to sildenafil analogues

• Said A. S. Ghozlan,
• Khadija O. Badahdah and
• Ismail A. Abdelhamid

Beilstein J. Org. Chem. 2007, 3, No. 15, doi:10.1186/1860-5397-3-15

• report results of our work aimed at exploring this synthetic methodology and adoption of products for the synthesis of pyrazolo[4.3-d]pyrimidines. Thus, compounds 1a-c, were prepared according to literature procedures via coupling of ethyl cyanoacetate with aromatic diazonium salts [10]. It has been