Tetramethylfluoroformamidinium

FIGURE 7.19 Reagents for preparing A-protected amino-acid fluorides,55-5661 Boc2-amino-acid fluorides (CyNF),58-59 and a nonbasic acid scavenger (BSA).62 CyNF = cyanuric fluoride DAST = diethylaminosulfur trifluoride TFFH = tetramethylfluoroformamidinium hexafluo-rophosphate BSA = b (trimethylsilyl)acetimide. 

TEMPO Tentagel Teoc TES Tf TFA TFFH 2,2,6,6-tetramethyl-l-piperidinyloxy PEG-grafted cross-linked polystyrene 2-(trimethylsilyl)ethoxycarbonyl triethylsilane trifluoromethanesulfonyl trifluoroacetic acid tetramethylfluoroformamidinium hexafluorophosphate, [(Me2N)2CF] [P F ]... 

Carpino LA, El-Faham A. Tetramethylfluoroformamidinium hex-afluorophosphate a rapid-acting peptide coupling reagent for solution and solid phase peptide synthesis. J. Am. Chem. Soc. 1995 117 5401-5402. 

The conversion in situ of N-protected amino acids into the corresponding fluorides via the use of a new reagent, tetramethylfluoroformamidinium hexafluorophosphate (30, TFFH) has been reported (Scheme 11). ° This discovery enabled the use of TFFH under conditions similar to those used for uronium or phosphonium reagents derived from HOBt or HOAt. 

Tetramethylfluoroformamidinium hexafluorophosphate. The reagent is prepared from tetramethylurea by consecutive reactions with POCI3, HPFjj, and KF, and finds use in mediating the condensation of acids and hydrazine (to form hydrazides) and of amines and CSj in the presence of EtjN (to form isothiocyanates). 

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