PyBrOP

PyBroP bromo(tripyrrolidino)phosphonium hexafluorophosphate TBS TBDMS, ferf-butyldimethylsilyl... 

A Stierandova, R Safar. Unexpected reactivity of PyBrop towards M/V-disubstituted formamides and its application, in HLS Maia, ed. Peptides 1994. Proceedings of the 23rd Peptide Symposium, Escom, Leiden, 1995, pp 183-184. 

The direct reaction of sodium phenoxide with the 2-pyrimidinone 185 has also been achieved using pyBroP as the coupling reagent <2005JOG1957>. 

Schreiber and co-workers (436) prepared a library calculated to contain 2.18 million polycyclic compounds through the 1,3-dipolar cycloaddition of a number of nitrones with alkenes supported on TentaGel S NH2 resin (Scheme 1.83). (—)-Shikimic acid was converted into the polymer bound epoxycyclohexenol carboxylic acid 376 (or its enantiomer), coupled to the resin via a photolabile linker developed by Geysen and co-workers (437) to allow release of the products from the resin in the presence of live cells by ultraviolet (UV)-irradiation. A range of iodoaromatic nitrones (377) was then reacted with the ot,p-unsaturation of the polymer-bound amide in the presence of an organotin catalyst, using the tandem esterification/ dipolar cycloaddition methodology developed by Tamura et al. (84,85) Simultaneous cyclization by PyBrop-mediated condensation of the acid with the alcohol... 

The difficulties encountered in aminoacylation of such lipo-amino acid derivatives are similar to those of the N-alkylated amino acids (see Vol. E 22c, Sections 10.1.1 and 10.1.2), but may be even worse due to steric hindrance of the large alkyl chains. Similarly, acylation with such amino acids leads to poor yields by the use of even stronger acylating reagents, e.g. HBTU, BOP, and PyBroP, with a marked improvement by the use of the mixed anhydride method although long reaction times were required. 128 ... 

Figure 1 Proportion of the Xaa(P)-Deleted Peptide, ASQGLEDPA-NH2, Determined in Crude Products Obtained from the PyBroP/DIPEA, BOP/HOBt/NMM, BOP/HOBt/DIPEA, HBTU/HOBt/DIPEA, HATU/ HOAt/DIPEA, and HATU/DIPEA Coupling of Fmoc-iyr[PO(OBzl)(OH)]-OH (Y), Fmoc-Ser[PO-(OBzl)-(OH)]-OH (S), and Fmoc-Thr[PO(OBzl)(OH)]-OH (T) (3 equiv) for 1 hJ4Sl b...

The incorporation of derivatives Fmoc-Ser[PO(OBzl)(OH)]-OH (18) and Fmoc-Thr[PO(OBzl)(OH)]-OH is best effected using uronium reagents such as HBTU/HOBt/ DIPEA and HATU/HOAt/DIPEA since both BOP and PyBroP failed to effect complete incorporation in comparative test couplings. 48 In a separate work, the BOP/HOBt/DIPEA coupling of Fmoc-Ser[PO(OBzl)(OH)]-OH was found to be only 85% complete after double coupling and the incorporation of the anionic phosphorodiester caused a decrease in the coupling efficiency of following residues. 94 Despite these potential problems, both Fmoc-Ser[PO(OBzl)(ONa)]-OH and Fmoc-Thr[PO(OBzl)(ONa)]-OH have been successfully employed for the Fmoc-based solid-phase synthesis of various Ser(P)- and Thr(P)-... 

Peptide synthesis reagents such as diisopropylcarbodiimide (DIC), benzotriazole-1-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate (PyBOP), bromo-tris-pyrrolidino-phosphonium hexafluorophosphate (PyBroP), 2-(lH-benzotriazole-l-yl)-l,l,3,3-tetramethyluronium hexafluorophosphate (HBTU), 1-hydroxybenzotriazole (FlOBt), piperidine, A-methylmorpholine (NMM), trifluoroacetic acid (TEA), triisopropylsilane (TIS), A -diisopropylethylamine (DIPEA, DIEA), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,2-ethanedithiol (EDT), and 4-dimethylaminopyridine (DMAP) may be obtained from Sigma-Aldrich, Chemlmpex, and Novabiochem. 

Couple a-O-Fmoc-protected hydroxyl acid using HBTU/HOBt or PyBroP protocol. 

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