Bis carbodiimides

The phosphoryl bis-carbodiimide 17 polymerizes in the solid state when stored for one week at 30 °C. A thiophosphoryl bis-carbodiimide 19 is also obtained from the bis-cyanamide precursor 18 and bis(diisopropylamino)chlorophosphane with subsequent oxidation with elemental sulfur. 

The 1,3-dipolar addition of phenylazide to metal coordinated ligands affords carbodi-imide ligands. An example is the reaction of the bis-azidopalladium complex 38 with two equivalents of 2,6-dimethylphenyl isocyanide to give the bis-carbodiimide complex 39. ... 

Macrocyclic bis-thioureas 17, on treatment with PhsP and CCU/EtsN, afford cyclic bis-carbodiimides 18. °... 

The homopolymerization of carbodiimides affords polyguanidines, which are nylon-1 imides. Because of their thermal instability, the homopolymers have found no utiUty as industrial polymers. Polyguanidines are also obtained in the reaction of hexamethylene-bis(t-butylcarbodiimide) with diamines. The polyaddition reactions of bis-carbodiimides with dialcohols and dithiols also produce the corresponding addition polymers. In the reaction of hexamethylene-bis(t-butylcarbodiimide) the polyaddition reactions proceed across the less sterically hindered C=N bond. Masked bis-carbodiimides, which are thermally unblocked, are also used in crosslinking reactions. 

Thiophene-2,5-bis-iminophosphoranes are converted to the corresponding bis-carbo-diimides using aryl isocyanates but the bis-carbodiimides were converted in solution to the corresponding bis-guanidines. ... 

Bis-carbodiimides are also used to crosslink butadiene/acrylonifrile copolymers containing carboxyl groups Also, blocked dicarbodiimides are used in the crosslinking of carboxyl functional poly(methacrylates). ... 

Polycarbonate blends with polyQactic acid) have been compatibilized through addition of bis(isocyanate), bis(carbodiimide), oxazoUne-f-PS, or epoxy resin (Wang et al. 2012e Mukawa et al. 2011). 

A method for preparing cyclic bis(carbodiimide)s 1725 in up to 84% yield by reacting iminophosphoranes 1724 with B0C2O in the presence of DMAP at room temperature for 12 h has been developed [1266]. 

Typical procedure. Bis(carbodiimide) 1725 [1266] To a suspension of the bis(imino-phosphoiane) 1724 (0.69 mmol) in dry dichloromethane (20 mL) was added B0C2O (0.30 g, 1.39 mmol) and DMAP (0.083 g, 0.69 mmol). The resultant mixture was stirred under nitrogen at room temperature for 12 h. The solvent was then removed under reduced pressure, the resulting material was suspended in anhydrous ethanol (10 mL), and the soUd was collected by filtration, air-dried, and recrystallized from dichloromethane to give the bis(carbodiimide) 1725 in 84% yield mp 104—106 °C pale-yellow crystals IR (Nujol) Vmax = 2139 cm . ... 

The preparation and intramolecular cyclization of other bis(carbodiimide)s has been described. Treatment of 2,2 -bis[(triphenylphosphoranylidene)aminoj-biphenyl 1726 with carbon dioxide provides, through an intermolecular aza-Wittig reaction, the bis(carbodiimide) 1728 (6% yield), which reacts further in an intramolecular cydization to form diazetidine 1729 (28% yield) [1267]. 

Amorphous silicon bis(carbodiimide) has been identified as a reactive precursor for the synthesis of nitridosilicates. During the current... 

A bis(iminophosphorane) derived from 2,2 -diazidobiphenyl [or a 2,2 -bis(isothio-cyanato)biphenyl reacted with aryliminophosphoranes] serves as the entry point for bis(carbodiimides) and their intramolecular cycUzations to l,3-diazetidine-2,4-diimines. A mechanistic scheme for the aza-Wittig reactions is proposed. 

The synthesis, structures, and reactivity of neutral and cationic mono- and bis(guanidinato)zirconium(rV) complexes have been studied in detail. Either salt-metathesis using preformed lithium guanidinates or carbodiimide insertion of zirconium amides can be employed. Typical examples for these two main synthetic routes are illustrated in Schemes 73 and 74. Various cr-alkyl complexes and cationic species derived from these precursors have been prepared and structurally characterized. 

The facile insertion of carbodiimides into a Ti-CMe bond of (CsRslTiMes (R = FI, Me) (cf. Section 1II.B.2) has been extended to the insertion of optically pure (R,R)- and meso-(R,S)-1.3-bis(l-phenylethyl)carbodiimide. Treatment of Cp M(NMe2)3 (M = Zr, FFf) with both achiral and optically pure aminooxazoline proligands ITL yielded metastable aminooxazoline half-sandwich diamide... 

Oxalamidinate anions represent the most simple type of bis(amidinate) ligands in which two amidinate units are directly connected via a central C-C bond. Oxalamidinate complexes of d-transition metals have recently received increasing attention for their efficient catalytic activity in olefin polymerization reactions. Almost all the oxalamidinate ligands have been synthesized by deprotonation of the corresponding oxalic amidines [pathway (a) in Scheme 190]. More recently, it was found that carbodiimides, RN = C=NR, can be reductively coupled with metallic lithium into the oxalamidinate dianions [(RN)2C-C(NR)2] [route (c)J which are clearly useful for the preparation of dinuclear oxalamidinate complexes. The lithium complex obtained this way from N,N -di(p-tolyl)carbodiimide was crystallized from pyridine/pentane and... 

Cyanamide can be stannylated under various conditions to give bis(stannyl)carbodiimides (224-227), and bis(stannyl)sulfurdiimides have been prepared from the reaction between S4N4 and trimethyldi-methylaminotin (228). 

N,N-Bis(trimethylsilyl)carbodiimide 328, which is readily accessible in 81% yield on silylation of cyanamide with TCS 14/triethylamine [124] and which is apparently in equilibrium with N,N-bis(trimefhylsilyl)cyanamide 553, reacts readily with non-enolizable ketones such as 554 or 2,5-dimethyl-p-quinone in the presence of CsF or TiCL., probably via 553, to N-cyanoimines such as 555 or 556, in 47 and 89% yield, respectively, and HMDSO 7 [125, 126] whereas the enohzable ketone... 

Reactions of 2,3-dioxo-l,2,3,5,6,7-hexahydropyrido[l,2,3-carboxylic acids and the homologous acetic and propionic acids, prepared by basic hydrolysis of the corresponding ester, with amines, 28% NH4OH, and hydroxylamine derivatives in the presence of l-ethyl-3-[3-(dimethylamino)propyl]carbodiimide and hydroxybenztria-zole <1995BML1527>, 1995BML1533>, and in the presence of NEt3 and A, A -bis(2-oxo-3-oxazolidinyl)phosphinic... 

Raasch, and Schaumann and co-workers, have studied the reactions of bis (trifluoromethyl)thioketene (83 R1 = CF3) with alkenes, with thioketones, and with carbodiimides or Schiff-base imines. The products were, respectively, thietans, 1,3-dithietans (84 R1 = CF3), and 1,3-thiazetidines (85 R1 = CF3) (from the carbodiimide).114,115 With phenyl azide the 1,2,3,4-thiatriazoline (86 R = CF3) is formed subsequent pyrolysis yields2,l-benzisothiazole.114... 

The following protocol assumes the prior derivatization of an oligonucleotide at the 5 end using a bis-hydrazide compound according to the protocol of Section 2.1 (this chapter) using a carbodiimide-mediated reaction. 

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