Thio-bromo reaction

In this final example of the broad applicability the thiol moiety has within conjugative chemistry, the nucleophilic thio-bromo reaction is beginning to make an impact in macromolecular science. Typically, a base such as triethylamine is used to deprotonate the thiol, which can then efficiently react with a-bromoesters in a thio-etherification reaction. 

Figure 2.13 The use of the thio-bromo reaction to achieve highly branched polymers from monodis-perse polymer precursors (Xu et al, 2009). (Reproduced with permission from A.J. Inglis and C. Bamer-Kowollik, Ultra rapid approaches to mild macromolecular conjugation, Macromolecular Rapid Communications, 2010, 31, 14, 1247-1266. Wiley-VCH Verlag GmbH Co. KGaA.)...

An additional interesting observation is that the thio-bromo reaction is kinetically favored over the competing disulfide formation that must always be considered in such systems. The thio-bromo click reaction is obviously very convenient in that it makes use not only of readily available materials, but also some of the most common end groups encountered in modern polymer chemistry. It therefore has the potential to become a valuable addition to the click chemistry toolbox. 

Figure 8.5 Iterative two-step divergent approach by thio-bromo reaction and subsequent acylation (Brad et al, 2009). (Reprinted from M.R. Brad, L. Gerard, H. Christian and R Virgil, Synthesis of dendrimers through divergent iterative thio-bromo click chemistry, Journal of Polymer Science, Part A Polymer Chemistry, 2009, 47, 15, 3931-3939 (Scheme 1), 2009, with the permission of John Wiley Sons, Inc.)...

Figure 8.10 One-pot preparation of hyperbranched polymers using thio-bromo reaction. (Reprinted with permission from J. Xu, L. Tao, C. Boyer et al, Combining thio-bromo click chemistry and RAFT polymerization A powerful tool for preparing functionalized multiblock and hyperbranched polymers, Macromolecules, 43, 1, 20-24, 2010. 2010 American Chemical Society.)...

Purines, N-alkyl-N-phenyl-synthesis, 5, 576 Purines, alkylthio-hydrolysis, 5, 560 Mannich reaction, 5, 536 Michael addition reactions, 5, 536 Purines, S-alkylthio-hydrolysis, 5, 560 Purines, amino-alkylation, 5, 530, 551 IR spectra, 5, 518 reactions, 5, 551-553 with diazonium ions, 5, 538 reduction, 5, 541 UV spectra, 5, 517 Purines, N-amino-synthesis, 5, 595 Purines, aminohydroxy-hydrogenation, 5, 555 reactions, 5, 555 Purines, aminooxo-reactions, 5, 557 thiation, 5, 557 Purines, bromo-synthesis, 5, 557 Purines, chloro-synthesis, 5, 573 Purines, cyano-reactions, 5, 550 Purines, dialkoxy-rearrangement, 5, 558 Purines, diazoreactions, 5, 96 Purines, dioxo-alkylation, 5, 532 Purines, N-glycosyl-, 5, 536 Purines, halo-N-alkylation, 5, 529 hydrogenolysis, 5, 562 reactions, 5, 561-562, 564 with alkoxides, 5, 563 synthesis, 5, 556 Purines, hydrazino-reactions, 5, 553 Purines, hydroxyamino-reactions, 5, 556 Purines, 8-lithiotrimethylsilyl-nucleosides alkylation, 5, 537 Purines, N-methyl-magnetic circular dichroism, 5, 523 Purines, methylthio-bromination, 5, 559 Purines, nitro-reactions, 5, 550, 551 Purines, oxo-alkylation, 5, 532 amination, 5, 557 dipole moments, 5, 522 H NMR, 5, 512 pJfa, 5, 524 reactions, 5, 556-557 with diazonium ions, 5, 538 reduction, 5, 541 thiation, 5, 557 Purines, oxohydro-IR spectra, 5, 518 Purines, selenoxo-synthesis, 5, 597 Purines, thio-acylation, 5, 559 alkylation, 5, 559 Purines, thioxo-acetylation, 5, 559... 

Neighboring-group participation reactions by sulfur and nitrogen functions have also been observed for deoxyhalogeno sugars. An example is the formation of the anhydride 146, which possesses an oxathiabicyclo[2.2.2]octane ring-system constrained in a boat-like conformation, on treatment of methyl 4-0-benzoyl-2-S-benzoyl-6-bromo-6-deoxy-2-thio-Q -D-altropyranoside (145) with methanolic... 

JOC4257). In the reaction of monobromo compounds (486) and (487) with piperidine, the major products are normal ones with 3-bromobenzo[6]thiophene (487) a small amount of the cine substituted product (489) is formed (Scheme 166). 2,3-Dibromobenzo[f>]thio-phene (488) initially gives the 2-piperidino-3-bromo derivative (490) at 106 °C, which is debrominated to (489) at 180 °C. This result suggests that the small amount of (489) from (487) might arise through a transbromination-debromination sequence (73JOC1365). 

The Hunsdiecker reaction has been used only twice as a potential source of bromobenzo[6]thiophenes with 3-bromo-5-nitrobenzo[6]-thiophene-2-carboxylic acid it proceeds normally to give 2,3-dibromo-5-nitrobenzo[6]thiophene,152 but with 5-nitrobenzo[6]thiophene-2-carboxylic acid the main product is 3-bromo-5-nitrobenzo[6]thio-phene-2-carboxylic acid, accompanied by smaller amounts of 2,3-dibromo-5-nitrobenzo[6]thiophene.152 497... 

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