Formamidinium

Disulfide dications are remarkably stable to water, in contrast to disulfonium dications. However, all they can be hydrolyzed by alkali water solution to give starting thiocarbonyl compound or more hydrolyzed product. For example, exposition of salt 157 to the aqueous NaOH gives formamidinium salt 158 and thiourea (Scheme 60).154... 

Anthrapyrimidine and its substituted derivatives are obtained by condensation of 1-aminoanthraquinone (or its derivatives) with formamide or aqueous form-aldehyde/ammonia in the presence of an oxidant, such as ammonium vanadate or m-nitrobenzosulfonic acid. A newly developed, more simple route proceeds via formamidinium chloride, which is prepared from 1-aminoanthraquinone with di-methylformamide and thionyl chloride or phosphorus oxychloride. Cyclization in a solvent in the presence of ammonium acetate affords the desired product ... 

A recently published new synthesis of dinitrosomethanides salts (DNM = rfinitroso-methanide) starts from formamidinium nitrate (8), which represents an easily accessible source for an NC(H)N unit . Treating a methanolic solution of 8 and hydroxylammonium nitrate (two equivalents) with a methanolic solution of KOBu-t (two equivalents) results in the formation of the labile intermediate Af,Af -dihydroxyformamidinium nitrate (9) (Scheme 8). The reaction of 9 with MOBu-t (two equivalents, M = alkali metal) in the presence of oxygen yields the deep blue alkali DNM salt (7), which can easily be purified by recrystaUization from methanol (yield 60-70%) . 

Similar to their spontaneous 1,4-hydration in water, heterocycles 49a, 50a-e, and 50g all react simply upon dissolution in warm methanol to form his-addition products. The X-ray crystal structure of the bis-methanol adduct (51) derived from the diazaborine 50b clearly showed it to be a zwitterion comprised of tetrahedral borate anion and formamidinium cation fragments. Once again, 50f proved to be the only exception A weakly chelated dimethylborate ester (not shown) was found to be its structure in MeOH by B NMR. 

Table 4.76. 13C Chemical Shifts of Selected Carbenium Ions in Magic Acid (SbF5/FS03H/S02ClF) between -40°C and -80°C [79, 492] (5C in ppm). (Guani-dinium chloride and formamidinium chloride (last entries) are measured in hexa-deuteriodimethyl sulfoxide at room temperature.)... 

Treatment of orthoamide 123 with equimolar amounts of aqueous hydrochloric acid yielded the salt 124 from which 123 can be regenerated by neutralization. NMR indicates that salt 124 and bicyclic formamidinium ion 126 interconvert rapidly at 70°C. This is explained by a conformational change from 124 into 125 which permits elimination of the amine group with stereoelec-tronic control (125 126). Finally, addition of excess hydrochloric acid to orthoamide 123 precipitated the bicyclic dichloride 127. 

Reaction of dyes containing a primary amino group with dimethylformamide and an inorganic acid chloride, e.g., phosphoryl chloride, permits introduction of the formamidinium group (e.g.,57), which is also scissioned off upon heating in the dye bath [154], A similar reaction occurs with the trialkylhydrazinium moiety obtained by reacting formyl-substituted azo dyes with dialkylhydrazines and subsequent quatemization [155],... 

Azapurines were also synthesized by the condensation of 5-amino-l,2,3-triazole carboxamides 118 or 119 with formamide or with formamidinium acetate. When the triazole carried neutral substituents at N-l such as in 118, the expected 8-azapurin-6-ones 121 were formed, but when an acidic substituent was present in the same positions as in 4-carboxyphenyltri-azolamide 119, the condensation reaction gave a mixture of 6-amino-8-azapurine 120 together with 121 in addition to a small amount of Dimroth isomer 122. However, reaction of 119 with triethyl orthoformate gave a mixture of azapurine 121 and an excess of the isomeric triazole 122 (80FES308 90CZ246) (Scheme 24). 

A series of vinylogous formamidinium salts and formamidines were reduced at the enamine and iminium double bonds by NaBH4 giving the corresponding 1,3-dia-minopropanes138,139 (Scheme 103). 

MACROLiDEs Chloiomethyl methyl sulfide. Dialkylhoryl trifluori imethanesulfonate. Di-n-hutyltin oxide. Dichloroketene. 4-Di-methylamino-3-butyi e-2-one. Keteny 1 i-dene triphenylphospl orane. Tetra-n-butyl-ammonium fluoride. 1,1,6,6-Tetra-n-butyI-1,6-distanna-2,5,7, lO-tetraoxycyclodecane. Tetrakisftriphenylphdsphine)-palladium. N,N,N,Nl-Tetramethylchloro-formamidinium chloride. 

Ammoninm (Piperidino-methyl)-trimethyl- -bromid E16a, 1008 (N-Aminomethylier.) Formamidinium N,N -Dimethyl-N,N -dipropyl-(iodid) E5, 94 (N-Alkylier.) N,N,N, N -Tetraethyl- (methylsulfat) E5, 90 (OR - NR2) Piperidinium l-(Dimethylamino-methyl)-l-methyl- -bromid E16a, 1008 (N-Aminomethylier.)... 

Formamidinium N,N -Di-tert -butyl-N,N -dimethyl- (iodid) E5, 94 (Amidin + R—1)... 

In these redox reactions, the thiourea reduces tellurium to Te(II) and is itself oxidized to formamidinium disulfide (126). The complexes are stable in the solid state as well as in acidic solutions and in organic solvents in water they tend to hydrolyze with subsequent disproportionation of tellurium into Te(0) and Te(IV). The square planar complexes of the Te(tu )2Y2 type have normally the cis configuration, but... 

Deprotonation of formamidinium salts is by far the most popular way to generate diaminocarbenes [3]. A major advantage of this method is that deprotonation is a rapid reaction, even at low temperatures. However, hindered strong anionic bases are required, especially for open-... 

Phosphorus nitrile chloride forms adduct (10) with DMF in the ratio 1 4, which is useful for the preparation of formamidines and azavinylogous formamidinium salts. It is supposed that the dehydration of primary amides to nitriles with (PNChls as well as the formation of 2-alkylbenzothiazoles from 2-(methylthio)anilides and (PNChls in the presence of triethylamine proceed via similar adducts." ... 

The reaction of amine hydrochlorides with thioxoesters affords amidinium salts (155 equation 91). Formamidinium salts (156 equation 92) with bulky substituents at the nitrogens can be obtained by oxidation of AA A/ -trisubstituted or AA -disubstitut thioureas with peracetic acid. - Byproducts in this reaction can be ureas and thiourea trioxides. -Dimethylaminoacrolein reacts with dimethylamine hydrochloride to give (157 equation 93), the parent compound of the vinylogous amidinium salt series. - From AA -dimethylthiobenzamide and Al-sulfinyldimethylammonium tetrafluoroborate the benzamidin-ium salt (158 equation 94) was prepared. ... 

Ketene aminals can be transformed by various electrophilic reagents to amidinium salts, thus mineral acids, alkyl halides, A///-dialkyliminium salts, alkoxymethyleneiminium salts, formamidinium salts, acyl halides, diazonium salts, vinylogous amidinium salts,sulfonyl halides, ketene dichlorides ... 

An important synthesis for formamide acetals with bulky alkoxy groups or with -aryl substituents starts from the corresponding formamidinium salts or from bis(didkylamino)acetonitriles the reaction with alcoholic alkoxides furnishes the amide acetals (449 Scheme 83).7 -32.35 ju tjjg reaction of the azavinylogous formamidinium salt (450) with methanolic methoxide a mixture of -dimethylform-amide dimethyl acetal and its azavinylogous derivative is produced. 

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