Alkyl carbodiimides

This method may be applied to the synthesis of a variety of aryl and alkyl carbodiimides. Other catalysts may also be used,10 but the especially active one described here is the one most easily obtained. The method is superior to other methods... 

Even methanol can be used for the dehydrochlorination of the chloroformamidines, as shown in the reaction of chlorodiazadienes 34 to give N-trichloromethylcarbonyl-N -alkyl-carbodiimides 35. ... 

Analogous mean of formation of the guanidine C=N bond was achieved mecha-nochemically by Friscic et al. by coupling of arylsulfonamides 271 and carbodiimides 272 (Scheme 3.72) [48], Guanidines 273 were prepared in high yields when alkyl carbodiimides were applied (Table 3.35). However, TMS and p-tolyl carbodiimides did not afford product, and p-tolyl carbodiimide reacted only when CuCl was added as catalyst in combination with nitromethane for LAG (entry 6). Environmentally friendly organic synthesis was achieved with solvent-free workup reaction mixture was milled with and Na2H2EDTA for short time (10 min, 25 Hz) and the product simply collected by filtration. 

Garbodiimide Formation. Carbodiimide formation has commercial significance in the manufacture of Hquid MDI. Heating of MDI in the presence of catalytic amounts of phosphine oxides or alkyl phosphates leads to partial conversion of isocyanate into carbodiimide (95). The carbodiimide (39) species reacts with excess isocyanate to form a 2 + 2cycloaddition product. The presence of this product in MDI leads to a melting point depression and thus a mixture which is Hquid at room temperature. 

Gyanamides and Derivatives A/-Chloro-/-alkylcyanamides, RN(C1)CN, are oils that have medicinal and other appHcations (99). Primary and secondary alkyl-A/-chlorocyanamides add photochemically to olefins yielding 1 1 adducts. By contrast, A/-chloro-A/-/-butylcyanamide initially rearranges photochemically to A/-chloro-Af-/-butylcarbodiimide, (CH2)3CN=C=NC1, prior to addition to olefins giving carbodiimides (67,100). 

Cycloadditions of isocyanates and their derivatives with vinyiaziridines were first reported by Alper and coworkers. From their previous studies of cydoadditions to vinylepoxides or alkylaziridines, they investigated cydoadditions to vinyiaziridines and found that such reactions with isocyanates, carbodiimides, or isothiocyanates in the presence of catalytic amounts of Pd(OAc)2 (2 mol%) and PPh3 (10 mol%) at room temperature afforded five-membered ring products 249 in 34—97% yields (Scheme 2.61) [91]. When an aziridine 247 possessing an alkyl substituent at the... 

Homoleptic lanthanide(III) tris(amidinates) and guanidinates are among the longest known lanthanide complexes containing these chelating ligands. In this area the carbodiimide insertion route is usually not applicable, as simple, well-defined lanthanide tris(alkyls) and tris(dialkylamides) are not readily available. A notable exception is the formation of homoleptic lanthanide guanidinates from... 

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. 

A useful method to synthesize ten and fourteen-membered ring imides 346 involved an initial condensation of macrocyclic -ketoestes 343 with alkyl or aryl isocyanates and carbodiimides, respectively, in the presence of a base [68]. After a nucleophilic attack of the enolate on the isocyanate C, the resultant amide N anion 344 induced a ring closure by addition to the keto group. Then, the intermediately formed four-membered ring 345 underwent a fragmentation... 

The present procedure2 describes the conversion of resin-bound, primary aliphatic amines into isothiocyanates and the conversion of the latter into 3-aminothiophenes. The generation of isothiocyanates is related to known procedures,3 in which amines are first treated with carbon disulfide and the resulting dithiocarba-mates are desulfurized by treatment with a condensing agent (alkyl chloroformates, carbodiimides, lead or mercury salts, etc.). The presence of resin-bound isothiocyanates on the polystyrene support could be qualitatively ascertained by infrared spectroscopy (KBr-pellet strong absorption at 2091 cm-1). 

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