CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• persulfate by hypervalent iodine oxidants such as iodobenzene diacetate (PIDA, Scheme 28) [49], or iodobenzene bis(trifluoroacetate) (PIFA) [50]. Fu and co-workers proposed the reaction mechanism depicted in Scheme 28. PIDA reacted with CF3SO2Na under heating conditions to produce two radicals: CF3• along

• . Experimental and computational studies allowed the authors to propose the mechanism depicted in Scheme 32. First, the CF3 radical was generated from CF3SO2Na and PIFA. Then, addition of CF3• to the alkene gave the alkyl radical 59 that added to the ipso position of the heteroaryl group to form radical 60. Next

• , homolysis of the C–C σ-bond in 60 provided the more stable hydroxyalkyl radical 61. This radical was oxidised by PIFA to yield the cationic intermediate 62, which finally lost a proton to furnish the reaction product. 1,2-Bis-trifluoromethylation of alkenes: Alkenes were efficiently and chemoselectively bis

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• reagent. The reaction temperature and residence time are 80 °C and 3.5 min, respectively. This product further undergoes a coupling reaction in a packed column containing polymer-supported [bis(trifluoroacetoxy)iodo]benzene (PS-PIFA), which yields a seven-membered tricyclic intermediate with 50% yield

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• demonstrated that this in situ generated reagent works more efficiently in such cyclizations than the more frequently used PIFA reagent. For instance, cyclization of biaryl 35 to carbazole 36 was achieved using this indirect electrochemical approach (Scheme 14) [59][60]. The transformation represents the key

A one-pot synthesis of 3-trifluoromethyl-2-isoxazolines from trifluoromethyl aldoxime

• Raoni S. B. Gonçalves,
• Michael Dos Santos,
• Guillaume Bernadat,
• Danièle Bonnet-Delpon and
• Benoit Crousse

Beilstein J. Org. Chem. 2013, 9, 2387–2394, doi:10.3762/bjoc.9.275

• available reagents have been employed under metal-free conditions. A group [27] reported that the hypervalent iodine reagents (diacetoxyiodo)benzene (DIB) and phenyliodine bis(trifluoroacetate) (PIFA) could successfully promote the oxidation of aldoximes to the corresponding nitrile oxide. Those reagents

• 2 with PIFA in CH2Cl2 afforded the product in only 16% yield (Table 1, entry 4). Better results were obtained by employing DIB in CH2Cl2 as solvent, after which the product could be isolated in an acceptable yield (55%, Table 1, entry 3). [Bis(acetoxy)iodo]benzene (DIB) is a weaker oxidant than PIFA

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• ) reductive deoxygenation with LiEt3BH (super hydride). The thioketal protecting group was then removed under oxidative conditions with [bis(trifluoroacetoxy)iodo]benzene (PIFA) to yield ketone 10 in good yield (66% over three steps, Scheme 2) [78]. This approach allowed us to produce a sufficient amount of

Study on the total synthesis of velbanamine: Chemoselective dioxygenation of alkenes with PIFA via a stop-and-flow strategy

• Huili Liu,
• Kuan Zheng,
• Xiang Lu,
• Xiaoxia Wang and
• Ran Hong

Beilstein J. Org. Chem. 2013, 9, 983–990, doi:10.3762/bjoc.9.113

• 321004, China 10.3762/bjoc.9.113 Abstract A “stop-and-flow” strategy was developed for the chemoselective dioxygenation of alkenes with a PIFA-initiated cyclization. This method is conceived for the desymmetrization of seco-diene, and a series of substituted 5-hydroxymethyl-γ-lactones were constructed

• after hydrolysis. This strategy also differentiates terminally substituted alkenes and constitutes a potentially novel synthetic approach for the efficient synthesis toward velbanamine. Keywords: alkene; desymmetrization; dioxygenation; lactone; PIFA; velbanamine; Introduction Stictosidine-derived

• Recently, Tellitu, Dominguez, and co-workers reported an intramolecular oxyamidation of alkene 11 with phenyliodine(III)-bis(trifluoroacetate) (PIFA) (Scheme 3) [46]. The lactam 12 was originally assigned as an unstable intermediate, which should be subsequently reduced to pyrrolidine 13. It was

Diels- Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton

• Natsuno Etomi,
• Takuya Kumamoto,
• Waka Nakanishi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2008, 4, No. 15, doi:10.3762/bjoc.4.15

• indanetrione 8, but attempts with bromoindanone 18 resulted in no reaction even under reflux. Utilization of a milder oxidant phenyliodosyl bis(trifluoroacetate) (PIFA) [33] for the oxidation of phenolic indanone 20, derived from 18 by selective demethylation with magnesium iodide (MgI2) [34], gave

• bromoquinone 12 after modification of the workup protocol without aqueous sodium bicarbonate. The PIFA oxidation of phenols 19 [35] and 20 in the presence of methanol gave the corresponding monoacetals 13 and 14. DAR of indanetrione 8 and 1-methoxy-1,3-butadiene (7) in dichloromethane (CH2Cl2) proceeded

• : a) P2O5, CH3SO3H, CH2Cl2 or CHCl3 (67% for 17, 71% for 18); b) bromine, 1,4-dioxane, H2O, rt, 2 h (68%); c) CAN, CH3CN, H2O, 0 °C, 30 min (65%); d) MgI2 · 6H2O, benzene, Dean-Stark (81% for 19, 96% for 20); e) PIFA, H2O, CH3CN, rt, 30 min (86%); f) PIFA, CH3OH, CH3CN, 0 °C (74% for 13, 92% for 14