Library of Fluorescent Polysulfonamides and Polyamide Synthesized by Iridium-Catalyzed Direct C–H Amidation Polymerization

Abstract

Step-growth polymerization via C–H activation is an attractive technique due to its advantages such as atom- and step-economy, derived from the reduced the number of synthetic steps required for the overall process and elimination of organometallic byproducts. To expand the utility of C–H activation polymerization beyond C–C bond coupling, we recently developed a highly efficient direct C–H amidation polymerization (DCAP) involving C–N bond formation, as a green polymerization process for synthesizing polysulfonamides. Here, we present a full account of the use of DCAP in the preparation of a library of polysulfonamides and polyamide from various diamides and diazides. From extensive model studies, several directing groups were screened, and it was found that subtle design of the directing groups by altering the steric hindrance and chelating bond angle greatly affected the efficiency of C–H amidation. Five directing groups were selected and seven AA-type monomers and seven BB-type monomers of azides were designed. After optimizing the polymerization process, 25 examples of well-defined high-molecular-weight (up to 171.4 kDa) polysulfonamides and polyamide were prepared. Notably, even diamide monomers containing four reactive ortho-C–H bonds produced defect-free polysulfonamides without cross-linking, supported by 1H NMR spectroscopy and size exclusion chromatography (SEC) traces. Furthermore, many of these polysulfonamides emitted light via an excited-state intramolecular proton transfer (ESIPT) process as a result of tautomerization upon photoexcitation.

Inverse electron demand Diels–Alder reactions in chemical biology

“…For the synthesis of cyclopropenes containing a carbamate scaffold, DIBAL reduction agent is typically used to produce the appropriate alcohol, followed by carbamate formation and TMS removal. [104][105][106] Importantly, methylcyclopropenyl methanol cannot be isolated as it is prone to rapid polymerization upon concentration, where a one-pot synthesis is required. 106,107 The fast grow of IEDDA reaction in the bioorthogonal chemistry field is closely boosted with the advanced TCO synthesis methodology.…”

“…14g). 69,104,106 Faster reaction rates for this dienophile are expected if measured under purely aqueous conditions. Norbornenes, another class of cyclic dienophiles, offer an excellent balance between facile strain-promoted reactivity with tetrazines and overall chemical stability ( Fig.…”

“…Upon treatment with a fluorogenic tetrazine, rapid membrane staining was observed. 104 Following these studies, a TCO-tagged ceramide lipid and a reactive tetrazine were used for imaging Golgi structures and dynamics in live cells by 3D confocal and stimulated emission depletion (STED) microscopy. 210…”

Biomedical applications of copper-free click chemistry: in vitro, in vivo, and ex vivo

“…10 In addition, the Devaraj group used a cyclopropene group that could participate in iEDDA reactions with Tz. 76 It may be an alternative molecule of TCO with a similar second order reaction rate constant but smaller size for specic purposes. Based on these ndings, we consider click chemistry to be emerging as a valuable technique in biomedical elds as well as organic chemistry.…”

Mining Proteomes Using Bioorthogonal Probes

“…A wide variety of biological problems have been studied using tetrazine ligations, such as systemic glycan imaging in vertebrae (Agarwal et al, 2015), super-resolution imaging of Golgi dynamics (Erdmann et al, 2014), and the visualiza-tion of cellular DNA synthesis (Rieder and Luedtke, 2014). Cyclopropenes as a small dienophile partner for tetrazine ligations were first reported in 2012 (Yang et al, 2012). As a mini-tag, cyclopropene-decorated sugars and amino acids have since been reported as metabolic probes (Lang and Chin, 2014;Patterson et al, 2012).…”