Carbodiimides, diaryl-, reaction with

A one-pot protocol for the synthesis of 1-aryl-5-(N-aryl-N-aroylamino)-tetrazoles 247 from symmetrical diaryl carbodiimides 243 with sodium azide under phase transfer conditions in toluene at room temperature was developed by Ding and Weber. The carbodiimide 243 reacts with sodium azide to form a guanyl azide 244 which, after reaction with an aroyl chloride 245, imdergoes electrocycHzation to yield the substituted tetrazole 247 (Scheme 47). The reaction is limited to symmetrical diaryl carbodiimides. Di-aUcyl carbodiimides fail to react imder these conditions while asymmetrical diaryl carbodiimides lead to a mixture of tetrazole isomers [157]. 

The reaction of /V-aminotriazines 847 with diaryl carbodiimides led (88H161) directly to the new triazolotriazines 848, which display mesoionic character (Scheme 172). 

A (pentamethylcyclopentadienyl)iridium chelating guanidinate complex has been conveniently prepared by treatment of [Cp IrCl2]2 with N,N, N"-th-p-tolylguanidine and base in THF at room temperature followed by recrystallization of the green product from toluene and pentane (Scheme 154). Insertion reactions of the product with heterocumulenes (diaryl carbodiimides, aryl isocyanates) have been investigated. It was found that the complex serves as highly active catalyst for the metathesis of diaryl carbodiimides with each other and for the more difficult metathesis of diaryl carbodiimides with aryl isocyanates (cf. Section V.C). ... 

The palladium-phosphine-catalyzed cycloaddition reactions of vinyloxetanes 530 with aryl isocyanates or diaryl-carbodiimides led to 4-vinyl-l,3-oxazin-2-ones 531 or l,3-oxazin-2-imines 532, respectively (Scheme 101). In the absence of phosphine ligands (PPhs, bis(diphenylphosphino)ethane (DPPE), l,3-bis(diphenylphosphino)propane (dppp), no conversion of heterocumulenes was observed. Starting from fused-bicyclic vinyloxetanes, both types of cycloadditions proceeded in a highly stereoselective fashion, affording only the r-isomers of alicycle-condensed 1,3-oxazine derivatives <1999JOC4152>. 

Reaction of the 2,6-dimethyl derivative (337), or of the analogous 3,5-dithiones (341), with diaryl carbodiimides affords themesoionic [l,2,4]triazolo[l,5-cf][l,2,4]triazines (342) (Equation (44))... 

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