N-F-type reagents

In the presence of several equivalents of N-F-type reagents, " it is possible to perform the difluorination of enolates of ketones, amides, and enamines. The difluorination of nucleosides has also been performed with Selectfluor (Figure 2.11). ... 

Most reactions with electrophilic fluorinating agents involve transformation of a carbon-hydrogen bond to a carbon-fluorine bond at a carbon atom that is either sp hybridised or that bears a negative charge. Selective electrophilic fluorination at a tertiary sp carbon atom can be achieved with molecular fluorine but is very difficult with N-F type reagents. 

Lal89a has discussed the application of a new family of N—F -type electrophilic-fluorination reagents consisting of l-alkyl-4-fluoro-l,4-diazabicyclo[2.2.2]octane salts (37) whose preparation, patented by Banks89b, utilizes the reaction of elemental fluorine... 

There is now available a range of stable, easily handled, solid electrophilic fluorinating agents of the N-F type. These remarkable reagents are generally prepared by reaction of a neutral base [108] or a salt [109] with fluorine (Figure 3.16). 

Hexaarylhiimidazole Derivatives and N-F Type Fluorinating Reagents. Oliver, Edward Walter. Univ. of Delaware, Newark, DE, USA. Avail. UIVII, Order No. DA9906866. (1998), 107 pp. From ... 

Table 7. N-F Electrophilic Fluorinating Reagents Main Structural Types...

Oxathiazinone dioxides have been used for the synthesis of a new type of heterocyclic N — F reagent 4, which are obtained by direct fluorination of salts of the oxathiazinone dioxide derivatives 3 with a mixture of 5% fluorine in nitrogen at low temperatures.136 137 Isolation of the pure compound 4a or 4b is generally rather difficult and the material is not stable in air at room temperature. In contrast, 3-fluoro-l,2,3-benzoxathiazin-4(3//)-one 2,2-dioxide (4c) is a colorless, thermally stable solid with a melting point of 61 "C.137... 

We consider a nuclear wave function describing collisions of type A + BC(n) AC(n ) + B, where n = vj, k are the vibrational v and rotational j quantum numbers of the reagents (with k the projection of j on the reagent velocity vector of the reagents), and n = v, f, k are similarly defined for the products. The wave function is expanded in the terms of the total angular momentum eigenfunctions t X) [63], and takes the form [57-61]... 

Nielsen (81CS(18)135) prepared thieno[2,3-4]pyrimidin-4(3//)-ones in 43-90% yield by heating 2-acylaminothiophene-3-carboxylates (330) with phosphorus pentoxide, N,N -dimethylcyclohexylamine and an amine hydrochloride at 180 °C. By raising the temperature to 240 °C, thieno[2,3-4]pyrimidin-4-amines (331) were obtained in 27-34% yield (Scheme 92). Phenyl N,N -dimethylphosphorodiamidate [(MeNH)2P(0)OPh], a well-known reagent for the synthesis of 3-methyl-4-oxo-3,4-dihydroquinazolines (77S180), reacts with thiophene derivatives of type (330) to give 3-methylthieno[2,3-4]pyrimidin-4(3/f)-ones (78ACS(B)303). 

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