Salts bis-amidine

Johnston and coworkers reported in 2004 an enantioselective aza-Henry reaction of nitroalkanes with Boc-protected imines catalyzed by the mono-protonated chiral bis-amidine salt 61 (Scheme 10.58) [154]. This catalyst class was also found to be... 

Other paramagnetic bis(amidinate) iron(II) complexes of the type [But(NR)2]2Fe (R = Cy, Pr ) have been prepared analogously from the lithium amidinate salts and FeCl2- The coordination geometry around Fe is distorted tetrahedral (Scheme 137). 

The dilithium salt of a linked bis(amidinate) dianionic ligand, Li2[Me3 SiNC(Ph)N(CH2)3NC(Ph)NSiMe3] ( = U2L) was prepared in 69% yield according to Scheme 204 by reaction of dilithiated N,N -bis(trimethylsilyl)-l,3-diaminopro-pane with benzonitrile. ... 

Synthesis of 4,4 -(5-cyanobenzene)-l,3-bis[l,2,3,5-diselenadiazolyl] 28 was reported (Scheme 53) <1993CM820>. The starting material, 5-cyanobenzene-l,3-bis[iV,iV,iV1-tris(trimethylsilyl)carboxamidine] 329, was prepared by treatment of 1,3,5-tricyanobenzene 328 with 2equiv of lithium bis(trimethylsilyl)amide, followed by transmetalation with trimethylsilyl chloride. Reaction of the bis(amidine) 329 with 4 molar equiv of SeCh affords the bis(l,2,3,5-diselenadiazolium) dication as its dichloride salt [28][Cl2]. Reduction of the dication with triphenyl-antimony affords compound 28 in 26% from the bis(amidine) 329. 

The amidine group can act as a binding site or a catalytic site at the same time. As will be described more in detail in Chapter 21, stable transition-state analogues for the basic ester hydrolysis like 14 or 16 can be used as bis-amidinium salts to get efficient enzyme mimics for the ester hydrolysis of 15 [29] and 17. In case of 17, even enantioselective reactions are possible [60]. 

Addition of anhydrous LiX (X = OH, Cl, Br, 1) to Li[Bu"C(NBu%] in THF afforded laddered aggregates in which two neutral lithium amidinates chelate one LiX unit. When the added salt is Lil, the monomeric laddered aggregate is isolated as a bis-THF adduct. In the case of LiOH, LiCl, and LiBr, the ladders dimerize about their external LiX edges. This process is highlighted in Scheme 10 for LiOH. The molecular structure of the resulting dimeric ladder complex is depicted in Figure 2. °... 

Reaction of the 5-substituted aminothiadiazole (88 R = Bu ) with aryl nitriles produced amidines (89) in yields dependent on the reactivity of the nitriles (Scheme 14). Decreasing the electron density of the cyano group by such electron-withdrawing groups as p-nitrophenyl-, and 2- and 4-cyanopyridyl, led to higher yields as compared to unsubstituted benzonitrile. A bis thiadiazole (92 R = Bu ) was prepared by reacting the sodium salt of (88) with 2-methanesulfonyl-5-(-butyl-1,3,4-thiadiazole (91) <84JHC1377>. 

The same research group <1994JPR266> expanded the synthesis to encompass diamidinium salts. Using dithioether spacers between amidine units, three alkyl-dithio-bis(l,2,3,5-dithiadiazolium) salts were synthesized (compounds 61-63), from the respective diamidine salts (Equation 8), in yields of 90%. 

Particle size, polymerization rate, ai solid content of the final latexes remain unchanged compared with polymerizations with the unreacted individual components of the inisurfe (water soluble non-surface-active azo-bis (di-isobutyric acid amidine) and a C15-alkylmonosulfonate as emulsifier in the case of Inisurf 4 and a potassium salt of co-aminoundecanoic acid as emulsifier in the case of Inisurf 5, respectively). 

The related 6-6 bicyclic system, 2,10-diazabicyclo[4.4.0]dec-l-ene (3), was prepared from frani-decahydro-1,8-naphthyridine [9] and an alternative method via direct cyclization of bis(3-aminopropyl)malonic acid was developed for large scale operation [10]. Heinzer et fl/. [ 11 ] reported the preparation of a sterically strongly hindered bicyclic amidine, 3,3,6,9,9-pentamethyl-2,10-diazabicyclo[4.4.0]dec-l-ene (Eschenmoser amidine) (4) (Figure 3.2) and its N-alkylated analogues and their potential uses in the formations of salts of carboxylic acids and related proton complexes of bidentate hgands (Section 3.3.8) [11b]. 

Hocker and Merten have reported on some reactions of bis-(l,3-diphenyl-2-imidazolidinylidene) (334) (Scheme 20). Cleavage of (334) with primary amines or hydrazines gives amino-amidines (335), whereas secondary amines give 2-amino-imidazolidines (336). The proposed mechanism is somewhat obscure. When (334) reacts with acyl sulphonyl amines the products are imidazolinium salts (337). 

Trifluoroacetamidine (585) is most widely used for the principal synthesis of pyrimidines. Compound 585 can be prepared from ethyl trifluoroacetate by ammo-nolysis, followed by dehydration with P2O5 and reaction with ammonia (Scheme 124) [335,336]. Amidine 585 has been introduced into reaction with various p-dicarbonyl compounds and their synthetic equivalents (Table 27), including p-ketoesters (Entries 1-6), in particular p-ketopyruvates (Entry 3) and a-alkoxymethylene-p-ketoesters (Entries 4-6), p-enaminocarbonyl compounds (Entries 7-9), malonic acid derivatives (Entry 10), fluorinated p-diketones (Entry 11), vinamidinium salts (Entry 12), a,p-unsaturated nitriles with leaving group at p position (Entries 13-15) and other bis-electrophiles (Entries 16, 17). Usually, the reaction gives moderate yields of the target 2-CF3-pyrimidines (ca. 50 %). 

---