PyBroP phosphonium hexafluorophosphate

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

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. 

Peptide coupling reagent bromotris(pyrrolidino)phosphonium hexafluorophosphate (PyBrOP) was used in synthesis of 10-membered succinyl bis(amide) 27 in 57% yield (Equation 3) <2002TL2593>. Similarly, 1,6-diazacyclo-decane substituted on only one nitrogen atom was prepared by reaction of A -trityl-protected linear triamine with succinyl anhydride. The amides were further reduced to amines using LAH <2002TL2593>. 

The chloro and bromo derivatives of phosphonium and uronium salts have not been extensively used in solid-phase strategy. Thus, chloro- and bromo-tris(pyrrolidino)-phosphonium hexafluorophosphate [PyCloP (63) and PyBroP (64)1 [109] and bromotris(dimethylamino)-phosphonium hexafluorophosphate (65) (BroP) [110], which have been used with success in solution for the synthesis of peptides containing A-methylamino acids, have not been found to be effective in the solid-phase mode. The active species detected for PyCloP, PyBroP, and BroP in the absence of HOBt are the symmetrical anhydride, the 5(4JT)-oxazolone, and, for Boc-amino acids, the iV-carboxyanhydride [99]. Furthermore, 2-chloro-l,3-dimethyl-4,5-dihydro-117-imidazolium hexafluorophosphate (66) (CIP, DCIH) [107,108,111] has been found effective only in the presence of 1 equiv. of HO At. 

PyBrOP bromo-tris-pyrrolidino-phosphonium hexafluorophosphate... 

Indeed, a general and facile one-pot procedure has been developed for the synthesis of 2-substituted pyridines from the corresponding pyridine A-oxides and nucleophiles as a good alternative to S Ar chemistry. A variety of nucleophiles and heteroaromatic A-oxides can participate in this reaction, proceeding effectively in the presence of PyBroP (bromo-fra-pyrrolidino-phosphonium hexafluorophosphate), the excellent agent for substrate activation (Scheme 17) [43]. 

It has recently been demonstrated that bromo-tns-pyrrolidino-phosphonium hexafluorophosphate (PyBroP) can be functiOTiing as a mild activator of azine N-oxide providing regioselective addition of Ai-nucleophiles (amines, sulfonamides, and NH-heterocycUc compounds) to pyridine, quinoline, and isoquinoline N-oxides (Scheme 53) [112,113]. A strong regiochemical preference for the orf/io-substitution pattern in aU these cases is likely caused by specific electrostatic attraction of nucleophilic species and the intermediate phosphonium salt 76. This synthetic procedure was successfully extended for other types of nucleophilic reagents (phenols, thiols, malonates). 

The phosphonium salts are important reagents in organic synthesis, which include PyBroP Bromotri(pyrrolidino)phosphonium hexafluorophosphate], BroP [Bromotris(dimethylamino)phosphonium hexafluorophosphate], PyBOP [(Benzotriazol-l-yloxy)tripyrrolidinophosphonium hexafluorophosphate], and BOP [(Benzotriazol-l-yloxy)tris(dimethylamino)phos-phonium hexafluorophosphate]. 

Although azidotris(dimethylamino)phosphonium hexafluo-rophosphate has not been used in solid-phase peptide synthesis, other commercial phosphonium salt derivatives such as Benzotriazol-l-yloxytris(dimethylamino)phosphonium Hexa fluorophosphate (BOP)," benzotriazoI-l-yloxytris(pyrroli-dino)phosphonium hexafluorophosphate (PyBOP), or bromotris(pyrrolidino)phosphonium hexafluorophosphate (PyBroP) are commonly used in that strategy. 

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