Amidine benzamidine

The synthesis of pyrido[2,3-d]pyrimidin-7(8H)-ones has also been achieved by a microwave-assisted MCR [87-89] that is based on the Victory reaction of 6-oxotetrahydropyridine-3-carbonitrile 57, obtained by reaction of an Q ,/3-unsaturated ester 56 and malonitrile 47 (Z = CN). The one-pot cyclo condensation of 56, amidines 58 and methylene active nitriles 47, either malonitrile or ethyl cyanoacetate, at 100 °C for benzamidine or 140 °C for reactions with guanidine, in methanol in the presence of a catalytic amount of sodium methoxide gave 4-oxo-60 or 4-aminopyridopyrimidines 59, respectively, in only 10 min in a single-mode microwave reactor [87,88]... 

Historically, the amidinate story begins with the discovery of N,N,N -tris(trimethylsilyl)benzamidine, PhC( = NSiMe3)[N(SiMe3)2], by Sanger. The compound was prepared by the reaction of benzonitrile with LiN(SiMe3)2 followed by treatment with chlorotrimethylsilane. The method was later... 

The lithium benzamidinates Li[PhC(NR)2] (R = Cy, Pr ) and Li[2,4,6-(Cp3)3C6H2C(NCy)2] have been prepared analogously. Reaction of FcLi (Fc = ferrocenyl) with 1,3-dicyclohexylcarbodiimide ( = DCC, Scheme 6), followed by addition of water, afforded the ferrocene-substituted amidine Fc(NCy)NHCy in 50% yield. The amidine is readily deprotonated by LLN(SiMe3)2 or NaN(SiMe3)2 to yield the alkali metal amidinates, Li[FcC(NCy)2l and Na[FcC(NCy)2l in high yields. ... 

Tin amidinates display a rich coordination chemistry with the metal in both the di- and tetravalent oxidation states. The first results in this area were mainly obtained with N-silylated benzamidinate ligands. Typical reactions are summarized in Scheme 48. A stannylene containing unsymmetrically substituted amidinate ligands, [o-MeC6H4C(NSiMe3)(NPh)]2Sn, has been prepared accordingly and isolated in the form of colorless crystals in 75% yield. ... 

While ytterbium(II) benzamidinate complexes have been known for many years/ the synthesis of the first divalent samarium bis(amidinate) required the use of a sterically hindered amidinate ligand, [HC(NDipp)2l (Dipp = C6H3Pr2-2,6)/ As illustrated in Scheme 54, the dark green compound Sm(DippForm)2(THF)2 (DippForm = [HC(NDipp)2] ) can be prepared by three different synthetic routes. Structural data indicated that hexacoordinated... 

A unique pair of stereoisomeric dimolybdenum amidinate complexes has been prepared and structurally characterized. The reaction of Li[PhC(NSiMe3)2] with dimolybdenum tetraacetate afforded trans- and ds-Mo2(02CMe)2[PhC (NSiMe3)2]2- While the acetates coordinate to the M02 core via a bridging mode in both compounds, the benzamidinates are bridging in the trans complex and... 

Two new amidine compounds (G6H2Ph3)G(N1Pr)2Al(CH3)2 and (G6H2Ph3)G(NCy)2Al(CH3)2 (Figure 21(c)) were prepared from the reaction of w-terphenyl-substituted amidines A,A -diisopropyl(or dicyclohexyl) benzamidine with trimethylaluminum.146 The 27A1 NMR showed broad peaks between <5=184 and 170 ppm. The coordination environment around the aluminum atoms is distorted tetrahedral. The acute N-Al-N (—69°) angle indicated considerable strain around the aluminum. 

Whereas, in imidates, an O-atom is attached to the sp2 C-atom, in another class of imines, the amidines, a N-atom is attached to the sp2 C-atom. Oxidative cleavage of benzamidines has been discussed (Chapt. 5 in [50]). Here, we present studies in which formamidines were examined (N-CH=N-R) as potential prodrugs of anti-HIV cytidine analogues [103]. Specifically, the... 

Experiments with mono- N-labeled amidines (the label is equally scrambled over both nitrogen atoms) have shown that in the 2-R-5-nitropyrimidines the excess of the enrichment is lower than that in the amidine (see Table III.2) (86JOC71). These measurements clearly indicate that during the reaction some labeling is lost. This result leads to the conclusion that besides formation of a mono- N-labeled 2-phenyl-5-nitropyrimidine (108), in which the N-label is scrambled over both nitrogens, a mono- N-labeled 2-phenyl-5-nitropyrimidine (109) is also obtained in which only one nitrogen is N-labeled (the benzamidine acts in this reaction as N-C donor) (Scheme III.55). 

Synthesis of tetrahydropyrido[2,3-,y pyrimidin-7-ones 537 in a microwave-assisted one-pot cyclocondensation of a,/3-unsaturated esters with active methylene compounds (malononitrile or methyl cyanoacetate) and amidine salts (guanidine or benzamidine) in NaOMe/MeOH for 10min has been reported <2003TL5385>. 

Triazinethiones are formed in good yields by the condensation of isothiocyanates and amidines. The reaction between ethoxycarbonyl isothiocyanate and benzamidine is used to illustrate the method (equation 68) (71CB1606). 

IV,N,N -Tris(trimethylsilyl)amidines have been used recently as precursors for a number of inorganic heterocycles and metallacycles,1 some of which are being studied in light of their unusual solid state properties2. Boere et al. reported the synthesis of several aryl-substituted persilylated benzamidines and the related compound /V,N,N, N",N",Ar" -hexakis(trimethylsilyl)-l,4-benezenedicarboximidamide (hereafter referred to as HBDA) 3 the present syntheses, which are generally based on the same reaction of an aryl-substituted carbonitrile with lithium bis(trimethylsilyl)amide, offer more facile routes to representative mono- and polyfunctional carboximidamides (i.e., amidines) as well as the prototypal derivative N,N,N -tris(trimethyl-silyl)formimidamide.4 As before, the crystalline diethyl ether adduct of lithium bis(trimethylsilyl)amide5 is favored over the nonsolvated amide in these syntheses the preparation of the diethyl ether adduct is also described here. 

Fig. 5 Complexes formed (a) between amidine groups in the functional monomer V,lV -diethyl-4-vinyl-benzamidine and carboxyl groups in the imprinting template IV-terephthaloyl-D-phenylglycine [82] and (b) between amidine groups in the imprinting template pentamidine and carboxyl groups in the functional monomer methacrylic acid [83]...

Amidines and thioamidines can also be viewed as urea-like binucleophilic compounds. There are a series of publications about their treatment with unsaturated carbonyls [7, 86, 87, 88, 89, 90, 91, 92]. The most general reaction products in this case are 1,4-dihydropyrimidines or 1,6-dihydropyr-imidines. Interaction of acetamidine 88 with mesityl oxide 52 [86] and benzamidine 90 with arylidenetetraline 91 [91] led to the corresponding 1,6-dihydropyrimidines 89 and 92, while the reaction of bezamidine and benzylideneacetone 24 yielded 1,4-dihydropyrimidine 93 [87] (Scheme 3.27). 

The yellow crystals of compound 23 (Equation 6) are routinely obtained in a yield of 10-30%. However, replacement of benzamidine with fV,iV,./V -tris(trimethylsilyl)benzamidine gives compound 23 in a 60% yield without the requirement for any acid scavengers, thus improving the ease of the purification process <1989J(P1)2495>. The mechanism and labile nature of the trimethylsilyl groups is illustrated in Scheme 2 (modified from <1989J(P1)2495>). On the basis of these findings, silylated amidines remain an attractive route to dithiadiazoles. 

Enamines derived from 2,2-disubstituted aldehydes (e.g. 261) react with N-chloro-N -aryl- and N-chloro-N - aroylamidines (262) according to two different pathways affording either imidazoline rings (264) or open-chain amidines (265)139 depending on the substituent at the enamine double bond and at the N atom of the benzamidine (equation 56). 

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