Hexamethyl phosphoric triamide HMPA

Intensive studies concerning the photoreductive cyclization of distinct ketones and aldehydes are made by Cossy et al. [170], They describe how bicyclic tertiary cycloalkanols 173 and 174 can be prepared from, s-un-saturated ketones 172 in good yields, initiated by photoinduced electron transfer from triethylamine in acetonitrile or by photoionization in pure hexamethyl-phosphoric triamide (HMPA) [171, 172], The reaction is stereo-, chemo- and... 

Cyclopentanols 214 and 217 are synthesized by intramolecular ketyl radical addition to tethered olefin by a photochemically induced electron-transfer activation of 8,co-unsaturated ketones 213 and 216, respectively, using either hexamethyl-phosphoric triamide (HMPA) or triethylamine in CH3CN [98] as solvent (see Scheme 8.59). 

The first reaction of this type was reported by Lippard et al. in 1988 the reaction of 2-cyclo-hexenone (3) with Grignard reagents in the presence of the chiral aminotroponeimine copper complex 5 as catalyst gave the 1,4-adducts 4 with 4- 14 % ee [3a]. The selectivity was increased to 74 % ee by addition of hexamethyl-phosphoric triamide (HMPA) and silyl halides [3b]. 

The synthesis of organolithiums according to Eq. (a) occurs in polar, aprotic solvents, such as tetrahydrofuran (THF), dimethoxyethane (DME) and hexamethyl-phosphoric triamide (HMPA). Hexamethylphosphoric triamide causes tumors and should be handled in a hood with appropriate protective measures. 

The thiocyanate complex of Ru(lll) is a basis of rather insensitive method (8 = 5.5-lO at 570 nm [15,62-64]. The complex is extractable into MIBK [14], chloroform in the presence of 1,10-phenanthroline [65], and hexamethyl phosphoric triamide (HMPA) in MIBK [66]. 

Rh(CO)43 under an atmospheric pressure of CO-H2 (1 1) in hexamethyl-phosphoric triamide (HMPA) solution at room temperature. ... 

Compounds containing the P(0)(N)n(0)3-n (n = 1, 2, 3), P(0)(N)m(0)2-mX (m = 1, 2, X = C, Cl, F, S etc.) and P(0)(0)3 moieties are among the weU-studied inorganic compounds [an interested reader may find many examples of compoimds with the mentioned skeletons through a CSD search, [1]]. N,N,N, N, N",N"-hexamethyl phosphoric triamide (HMPA, Scheme 1) is an important polar aprotic solvent with a high-dielectric constant [2] and an excellent ligand for interaction with hard metal-cations [3]. 

Reactivity enhancement has also been observed in the Smiles rearrangement involving non- or deactivated aromatic ring systems [44,45]. In the presence of hexamethyl-phosphoric triamide (HMPA), sodium hydride effects the transformation of 2-aryloxy-isobutyramides into N-aryl-2-hydroxyisobutyramides in good yield. Particularly noteworthy is the aryl ether to anilide conversion in 55% yield for the 4-methoxyphenyl compound. This reaction is formulated in equation 15.16. 

Synonyms HMPA HMPT HPT hexamethyl phosphoric triamide... 

For electrolysis with the hydrogen anode we use a mixture of THF and HMPA (hexamethyl-phosphoric triamide) with 0.02 M Et4NBF4 as solvent/electrolyte system. Trying to find a substitute for HMPA, we tested several rotic solvents, known to replace HMPA very effectively in organic synthesis (see Table 1). 

HMPA has the structure shown below, and the basic oxygen atom coordinates to lithium extremely powerfully. The cation is solvated, leaving the anion unsolvated and more reactive. HMPA is known to cause cancer, and should not be confused with its less common cousin HMPT (hexamethyl-phosphorous triamide). 

Alternative Names/Abbreviations Hexamethyl phosphoric triamide, hexametapol, HMPA... 

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