Diazirines fluoro

Some theoretical investigations have attempted to follow reactions of diazirines, among them reactions of 3-chloro- and 3-fluoro-diazirines. 

Diazirine-3,3-dicarboxylic acid, 1080 Difluorodiazirine, 0342 Dipotassium diazirine-3,3-dicarboxylate, 1340 3-Fluoro-3-(trilluoromethyl)-3//-diazirine, 0631 3-Methyldiazirine, 0808 3,3-Pentamethylenediazirine, 2422 Potassium hydrogen diazirine-3,3-dicarboxylate 3-Propyldiazirine, 1594... 

One example has been reported in which fluorine is replaced by an N-nuclcophilc with the intermediacy of a carbene species. Thus, when 3-fluoro-3-phenyl-3//-diazirine (2) is irradiated in the presence of a secondary amine, a diaminophenylmcthanc derivative 3 is formed.19... 

Diazetine, see Diazete, dihydro-Diazirines, calculations, 56, 373 Diazirine, 3-chloro-3-trifluoromethyl-, reaction with pyrrole, 59, 10 3//-Diazirine, 3-fluoro-3-methoxy-, 59, 3 Diazo coupling... 

Alkyl-3-fluoro-3Zf-diazirines have become more readily available since the exchange of halogen in 3-alkyl-3-halo(chloro or bromo)diazirines by fluoride was developed" (for mechanistic consideration of this process, see refs 49 and 50, for 3-bromo-3-trifluoromethyldiazirine, see ref 47). Until now only a few 1-alkyl-1-fluorocyclopropanes la and Ib have been prepared by this method (see Houben-Weyl, Vol. E19b, p 1028). 

Aryl-1 -fluorocyclopropanes 2 were synthesized by irradiation of a 3-aryl-3-fluoro-3//-diazirine and an alkene (2 > 300 nm, 25 °C) in a screw-top Pyrex Carius tube (Houben-Weyl, Vol. E19b, p980). The starting 3-aryt-3-fluoro-3//-diazirines were prepared from the corresponding 3-aryl-3-bromo-3//-diazirines and anhydrous tetrabutylammonium fluoride. The products were purified by column chromatography on silica gel (purity > 97%). Due to the explosive properties of diazirines, this method is not suitable for large-scale preparations. 

Similarly, photolysis of 3-fluoro-3-phenyl-3//-diazirine in 4-substituted styrenes, as well as 3-fluoro-3-(4-methoxyphenyl)-3//-diazirine in alkenes, resulted in the formation of 1-fluoro-1-phenyl-2-(4-substituted-phenyl)cyclopropanes 4 and 1-fluoro-1-(4-methoxyphenyl)cyclo-propanes 5 (in low yields), respectively. 

Fluoro-3-pyridyl-3//-diazirines were prepared from the corresponding chlorodiazirines by exchange reaction with anhydrous tetrabutylammonium fluoride in dry dimethylformamide (25°C, 15-20 hours). " ... 

Photolysis of 3-(3-fluoro-3//-diazirin-3-yl)-l-methylpyridinium iodide [obtained by qua-ternization of 3-fluoro-3-(3-pyridyl)-3//-diazirine] in 2-methylbut-l-ene afforded 3-(l-fluoro-2,2-dimethylcyclopropyl)-l-methylpyridinium iodide (3) via fluoro(pyridinio)carbene, the first carbene known which carries a cationic substituent. ... 

Alkoxy-3-chloro-3//-diazirines are obtained by the chlorination (aqueous sodium hypo-chlorite/dimethyl sulfoxide) of the corresponding amidines. They serve as precursors for the synthesis of 3-fluoro derivatives via the reaction with anhydrous tetrabutylammonium fluoride (for an improved procedure for the dehydration of commercial tetrabutylammonium fluoride trihydrate, see ref 26). This is a much simpler method than the earlier described preparation of 3-fluoro-3-methoxy-37/-diazirine involving the elemental fluorination reaction and a shatteringly explosive fluoronitrogen intermediate. 

Experimental procedures for the preparation of 3-chloro-3-phenoxy-3/f-diazirine ° and 3-fluoro-3-methoxy-3//-diazirine are given in Houben-Weyl, Vol. E19b, p 1655 and 1656, respectively for the preparation of dimethyl 3-chloro-3-methoxycyclopropane-tra s-l,2-di-carboxylate, see Houben-Weyl, Vol. E19b, pl657. 

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