Thiocyanation of BODIPY dyes and their conversion to thioalkylated derivatives

Abstract

Thiocyanation and formation of thioalkylated BODIPYs is a simple and reliable way for their chemical modification and photophysical tuning. ABSTRACTA high-yielding method for the direct thiocyanation of BODIPY dyes is described. In 1,3-dimethyl BODIPYs, the thiocyanato group adds at position 2, whereas the insertion occurs at position 5 in 3-amino BODIPYs. The transformation of the thiocyanato group enables the synthesis of thioalkylated BODIPYs. 2-Thioalkylated BODIPYs and 3-thiocyanato-5-piperidino BODIPYs exhibit interesting spectroscopical features. Hence, the described synthetic methodology can be used for the photophysical tuning of BODIPY dyes.

Synthesis of 3,8‐Dichloro‐6‐ethyl‐1,2,5,7‐tetramethyl–BODIPY from an Asymmetric Dipyrroketone and Reactivity Studies at the 3,5,8‐Positions

“…Furthermore, we anticipated that this methyl group could be regioselectively oxidized under mild conditions, providing functionality for further derivatization and/or conjugation of the BODIPY. [25] To illustrate these reactions, BODIPY 6c reacted with 4-formylanisole in the presence of p -toluenesulfonic acid and piperidine, in refluxing toluene for 72 h, regioselectively affording monostyryl-BODIPY 16 in 52% yield (Scheme 6). The monostyryl-BODIPY displays further redshifted absorbance and emission spectra (see below, Table 1 and Figure 7) and potential applications as a fluorescent sensor and photosensitizer.…”

Nitrogen Dioxide Catalyzed Oxidative Thiocyanation of Arenes with Ambient Air as the Terminal Oxidant

“…One starts with the reaction between the oxidative species and the aromatic rings to give the aromatic radical cations or a π complex . The other starts with the oxidation of SCN − to (SCN) 2 , SCN radical, or a reactive species with a pronounced SCN + character . To gain an insight into the reaction mechanism, we performed several control experiments in which the well‐known radical scavenger 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) was added to the reaction system.…”

“…However, SCN − is unreactive towards aromatic rings . An effective solution to this is the use of the oxidative strategy in which either SCN − or aromatic rings are oxidized in situ to the reactive species in the presence of various oxidants, for example, H 2 O 2 , K 2 S 2 O 8 , cyanuric chloride, oxone, NaClO 4 , 2,3‐dichloro‐5,6‐dicyanobenzoquinone, NH 4 VO 3 , and silica‐bonded vanadic acid …”

“…However,S CN À is unreactive towards aromatic rings. [1b] An effective solution to this is the use of the oxidative strategy [1b] in which either SCN À or aromatic rings are oxidized in situ to the reactive species in the presenceo fv arious oxidants, for example, H 2 O 2 , [5] K 2 S 2 O 8 , [6] cyanuric chloride, [4a] oxone, [7] NaClO 4 , [8] 2,3-dichloro-5,6-dicyanobenzoquinone, [9] NH 4 VO 3 , [10] and silicabondedv anadic acid. [11] Compared with the oxidants mentioned above,O 2 ,e specially air,i sabetter oxidant because it is inexpensive, readily available, and environmentally friendly,w hich has prompted many chemists to apply O 2 in the oxidation of organic substrates under the catalysis of various transition metals.…”

Síntese, caracterização e aplicações de fluoróforos derivados do BODIPY

“…170 Interessantemente, a inserção de uma piperidina à posição 3 do anel BODIPY parece aumentar a sua nucleofilicidade a ponto de possibilitar a aplicação dessa reação. Diante desses resultados, investimos no estudo da tiocianação direta de BODIPYs 3,5-substituídos.…”