Hexamethylphosphoramide compounds

Lithiochloromethyl phenyl sulfoxide 99 was found to react with aryl or alkyl halides in the presence of one equivalent of hexamethylphosphoramide to afford alkylated products 100 in high yields135. Thermal decomposition of these products in the presence of a catalytic amount of hydroquinone in xylene gave the corresponding vinyl compounds 101. 

Gas-liquid chromatography Diethyleneglycol monomethyl ether Partially or fully halogenated hydrocarbon Hexamethylphosphoramide Her Majesty s Stationery Office Compound of the same (organic) series Ignites on contact... 

Miconazole nitrate was prepared by Godefori and co-workers [5-7]. Imidazole 1 was coupled with brominated 2,4-dichloroacetophenone 2 and the resulting ke-tonic product 3 was reduced with sodium borohydride to its corresponding alcohol 4. The latter compound 4 was then coupled with 2,4-dichlorotoluene by sodium borohydride in hexamethylphosphoramide (an aprotic solvent), which was then extracted with nitric acid to give miconazole nitrate. 

Examples of alkali metal stannides are mainly limited to tris(trimethylsilyl)- and triphenylstannides. NMR studies of trimethyl- and tributylstannide in ether, THF, and hexamethylphosphoramide (HMPA, OP(NMe2)3) reveal the compounds to be monomeric in solution, as indicated by the large Li-Sn coupling. The addition of HMPA produces an... 

We have recently reported ( ) several synthetic studies of weak nucleophile SnAr reactions. In the latter cases (26f-1), new synthetic methodology was reported for the direct introduction of fluoroalkoxy groups into a variety of aromatic systems. These reports represent synthetically useful procedures for obtaining some otherwise inaccessible fluoroalkoxy materials but, unfortunately, they require the use of a dipolar, aprotic solvent (usually hexamethylphosphoramide, HMPA) and, in some cases, elevated temperatures. However, because of their diverse and important applications ( ), the syntheses of these and other organofluoro compounds continue to be of interest. For example, two recent reports of useful fluoroalkoxy materials include the insecticide activity exhibited by fluoroalkoxy substituted 1,3,4-oxadiazoles... 

DMF, and Nbl jSDMF have been shown to involve O-bonded DMF molecules by i.r. studies. The latter compound may be constituted as [Nb-(DMF)g]l4 since no bands attributable to Nb—I were observed, and this formulation is supported by preliminary conductance data in DMF solution. E.s.r. studies of NbCl4,2L complexes (L = DMF, DMA, THA, dioxan, dimethoxyethane, hexamethylphosphoramide, or AA -diethylformamide) indicate that they adopt a trans-octahedral geometry. 

A term, usually referring to a solvent, describing a compound which act neither as a proton donor nor a proton acceptor. Examples of polar aprotic solvents include dimethylformamide, dimethylsulfoxide, acetone, acetonitrile, sulfur dioxide, and hexamethylphosphoramide. Examples of nonpolar aprotic solvents include benzene and carbon tetrachloride. Studies of reactions in protic and aprotic solvents have demonstrated the importance of solvation on reactants, leaving groups, and transition states. Degrees of nucleophilicity as well as acidity are different in aprotic solvents. For example, small, negatively charged nucleophiles react more readily in polar aprotic solvents. It should also be noted that extremely... 

Tetrahydro-l,4-oxazin-2-ones can be deprotonated and then reacted with electrophiles. Thus, for example, the nonlabeled analog of compound 81 was deprotonated at the 3-position with sodium hexamethyldisilazide and ethylated using ethyl iodide. The reaction was performed in a 1 10 mixture of hexamethylphosphoramide (HMPA) and tetrahydrofuran <1998T10419>. If a dihalide is used and the oxazine has a free 4-nitrogen, cycloalkylation can be achieved as shown in the reaction of 219 to give 220 (Equation 17) <1993LA477>. 

Synthesis of 2,3-dihydro-l,4-dithiin 11 was accomplished from l,3-dithiol-2-one 247 in the presence of dibro-moethane and potassium hydroxide <1998JOG3952>, while reaction of 2,3-dichloro-l,4-dioxane with powdered Zn in hexamethylphosphoramide (HMPA) was used for the synthesis of 1,4-dioxene 10 <1998JPP10067773>. To obtain substituted 1,4-oxathianes, the hydrogenation of the corresponding partially saturated compounds has been employed <2001J(P1)2604>. 

Dinitrobenzene (5) has been converted to l-fluoro-3-nitrobenzene (6) with potassium fluoride in jV-methyl-2-pyrrolidone. Hexamethylphosphoramide can also be used as a solvent for this displacement reaction. Besides 5 some heterocyclic nitro compounds 7,9 were also converted to their respective fluoro analogs 8 and 10 by treating with potassium fluoride. 

Repeated inhalation of hexamethylphosphoramide by rats resulted in severe degenerative changes in renal convoluted tubules. Rats given this compound in the diet showed severe bronchiectasis and bronchopneumonia with areas of squamous metaplasia (lARC, 1977). 

The behavior toward Lewis bases was studied. The compound [R2A10CR NPh]2 did not form a stable complex with Lewis bases such as pyridine, tetrahydrofuran and triethylamine, as evidenced by IR spectroscopy, but did form with a strong bases such as trimethyl-amine oxide, Me3NO and hexamethylphosphoramide (Me2N)3PO. This fact means that the Lewis acidity of this organoaluminum is rather weak, because A1R3 forms the stable complex with a relatively weak electron donor compound such as diethyl ether and tetrahydrofuran, and R2A1NR2 with an electron donor such as triethylamine. 

HMPA hexamethylphosphoramide. This molecule that has been referred to as a potential carcinogenic compound , is now referred to as a useful aprotic solvent cf for instance, Sigma-Aldrich catalogue since edition 2000-2001, p. 921. 

N-Acylated indoles are converted into tricyclic compounds 211 in the presence of samarium diiodide (2.5 eq.) along with hexamethylphosphoramide (10 eq.) and phenol (2.0 eq.) as proton source <20030L4305>. 

In attempts to prepare 3-acyl-substituted BIPS (113), various salicylaldehydes were condensed with l,3,3-trimethyl-2-formylmethyleneindoline (Fischer s aldehyde). In alcohol, dimethylformamide, tetrahydrofuran, Y-mcthylpyrrolidonc. and hexamethylphosphoramide as the sole solvents, decarbonylation occurred and the only products were the BIPS compounds. However, in dimethyl sulfoxide, 5-nitro-and 3-bromo-5-nitrosalicylaldehydes gave 11 and 5.6% of the desired 3-formyl-BIPS, respectively. The structures were assigned from their IR and NMR spectra. 

There is a very extensive chemistry of compounds with P—N and P=N bonds for the most part the molecules are oligomeric or polymeric. Among the few relatively simple ones are (Me2N)3P and (Me2N)3PO (hexamethylphosphoramide), several X2P—NMe2 (X = Cl, F, and CF3), and PF3(NH2)2 (which has equatorial NH2 groups). The so-called PNP+ (sometimes PPN+) ion (Ph3PNPPh3) is widely used to isolate... 

N-Acylated indoles 1520 furnished tricyclic compounds 1521 in the presence of samarium diiodide (2.5 equiv) in tetrahydrofuran along with an excess of hexamethylphosphoramide (10 equiv) and phenol (2 equiv) as proton source (Equation 311) <20030L4305>. Whereas methyl ketone 1520 (R = Me) smoothly cyclized to compound 1521 (in 73% yield), the corresponding aldehyde 1520 (R = H) provided compound 1521 only in low yield (28%). 

The conclusions of Fenton and Zollinger are supported further by an investigation by the same authors on a syston in which no detectable amount of aminoazo, but only diazoamino compound is formed, namely the reaction of 4-chloro-benzenediazonium tetrafluoroborate with 4-chloroaniline in acetonitrile. The reaction is catalyzed markedly by relatively strong t ses in the order HjO < dimethyl-formamide < pyridine < DMSO < hexamethylphosphoramide. The order with respect to the last four additives is 1 with water it is less than one. This is strong evidence for a steady-state a j-complex. 

Hydrogen donors other than alcohols have been used for replacement of the diazonium group by hydrogen these include acetone, " tetrahydrofuran, - " dioxane, " dioxolane, " ethylene glycol dimethyl ether, "hexamethylphosphoramide (HMPA) and other compounds. "... 

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