L hexafluorophosphate

V Dourtoglou, J-C Ziegler, B Gross. L hexafluorophosphate de O-benzotriazolyl-AW-tetramethyluronium hexafluorophosphate a new and efficient peptide coupling reagent. Tetrahedron Lett 1269, 1978. 

E. Tricarbonyl[(l,2,Z,, 5-r))-2-methoxy-2,4 -cyclohexadien-l-yT -iron(l +) Hexafluorophosphate(l —). To the aqueous layer from Part D is added with swirling 7.1 g. (0.044 mole) of ammonium hexafluoro-phosphate (Note 23) in 30 ml. water. After 30 minutes, the light-yellow product is filtered, washed with water, and air dried the yield is about 9-10 g. (35-44%) (Notes 19, 24). 

B. Bis(2,4,6-trimethylpyridine)iodine(l) hexafluorophosphate. A 1-L, threenecked, round-bottomed flask equipped with a mechanical stirrer, condenser topped with a drying tube containing calcium chloride, and a stopper is charged with 500 mL of dry methylene chloride (Note 6), 82.5 g of bis(trimethylpyridine)silver(l) hexafluorophosphate (0.166 mol), and 41.9 g of iodine (0.165 mol). The mixture is stirred until all the iodine is consumed (1 hr - 2 hr) (Note 7). The resulting yellow solid (silver iodide) is suction filtered, and washed with 100 mL of dry methylene chloride. The filtrate is concentrated on a rotary evaporator at a maximum bath temperature of 30°C to give 68-76 g (80-88%) of yellowish solid bis(2,4,6-trimethylpyridine)iodine(l) hexafluorophosphate (mp 132-133°C) (Notes 8, 9, and 10). This product is suitable for reactions without further purification. 

It is important that all the iodine reacts with the silver salt. After concentration, the presence of iodine can cataly2e the decomposition of bis(trimethylpyridine)iodine(l) hexafluorophosphate. If necessary a small amount of silver salt can be added. 

PREPARATION OF BIS(2,4,6-TRIMETHYLPYRIDINE)IODINE(l) HEXAFLUOROPHOSPHATE AND BIS(2,4,6-TRIMETHYLPYRIDINE) BROMINE(I) HEXAFLUOROPHOSPHATE... 

Hept-6-en-l-ols undergo iodoetherification with bis(.ry/ -collidine)iodine(l) hexafluorophosphate in CH2CI2 (Scheme 12) to give 2-iodomethyloxepanes in high yields <1995SL323, 1996JOC5793>. 

Cinnamyl alcohols such as 95 were converted to the corresponding oxetane 96 by reaction with bis-(collidine)bromine(l) hexafluorophosphate (Equation 32) via a 4- r/o-/r7g-electrophilic cyclization <1999JOC81, 2001TL2477>. High yields of oxetanes (up to 88%) were only achieved with tertiary alcohols, with secondary alcohols giving mainly degradation products. 

Reaction of the ra-ene-5-yne carboxylic acid 977 with biscollidine iodine(l) hexafluorophosphate leads to exclusive formation of the C(6)-( )-iodovinyl tetrahydropyran-2-one 979. The product arises via attack of the acid onto the iodinium ion intermediate 978 (Scheme 258) <2004TL4503>. A similar iodolactonization of hex-5-enoic acid can be induced by Oxone -potassium iodide to furnish 6-(iodomethyl)tetrahydropyran-2-one in excellent yield (Equation 380) <2004SL368>. Similarly, treatment of 5-hexynoic acid with a polymer bound source of electrophilic iodide affords the tetrahydropyran-2-one 980 bearing a diiodo-substituted exocyclic double bond (Equation 381) <1999OL2101>. 

DICARBONYL(iis-CYCLOPENTADIENYL)(THIO-CARBONYL)IRON(l +) HEXAFLUOROPHOSPHATE(l -) AND DICARBONYL(iis-CYCLOPENTADIENYL)-[(METHYLTHIO)THIOCARBONYL]IRON... 

The bis(ry/ -collidine)iodine(l)hexafluorophosphate-promoted cyclization of unsaturated hydroperoxide 264 provided an excellent method for the production of the perhydro-dioxocin 265 in good yield (Equation 19) <2003T525>. 

Dourtouglou, V., Ziegler, J. C., and Gross, B. (1978) L hexafluorophosphate de 0-benzotriazolyl-Af,Af-tetramethyluronium un reactif de couplage peptidique nouveau et efficace. Tetrahedron Lett. 19, 1269-1272. 

Castro B, Dormoy JR, Evin G, Selve C. Reactifs de cou-plage peptidique IV (1) - L hexafluorophosphate de benzotri-azolyl A-oxytrisdimethylamino phosphonium (B.O.P.). Tetrahedron Lett. 1975 16 1219-1222. 

The resulting yellowish solid (silver bromide) is suction filtered and washed with 100 mL of dried methylene chloride. The filtrate is concentrated on a rotary evaporator at a maximum bath temperature of 30°C to give 65-74 g (83-95%) of bis(2,4,6-trimethylpyridine)bromine(l) hexafluorophosphate (mp 127-128 C) as a white solid (Notes 9,12, and 13). This product is suitable for reactions without further purification. 

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