Dibenzo-1,3a,4,6a-tetraazapentalene

Treatment of Polyfluoro-1,1-dihydroalkyl Sulfones with Sodium Cyanate and Triethylamine: A New Method for the Synthesis of 6-(Polyfluoroalkyl)uracils

“…Because of n-π conjugation, the exocyclic N(4)ϪC(4) bond is at 1.336(3) Å significantly shorter than the standard value for the N(sp 2 )ϪC(sp 2 ) single bond of 1.45 Å . [21] As an interesting peculiarity of the molecular structure 9a, one should note the strong [15] intramolecular H bond N(4)ϪH(41)···O(4) ''assisted by resonance''. [22] n the case of compound 7b, with the more lipophilic hexafluoropropyl substituent, treatment with ammonia proceeded in solution to give at least three products even with only 2 equiv.…”

The Aza Curtius Rearrangement

“…Because of n N Ϫπ CϭO conjugation, the N(2)ϪC(2) bond [1.310(3) Å ] is significantly shorter than the standard N(sp 2 )ϪC(sp 2 ) single bond value of 1.45 Å . [13] The geometric parameters of the intramolecular hydrogen bond O(1)···N(2) in 5 are unexceptional. [14,15] Carbodiimide 3a reacts with alcohols and secondary amines to give the corresponding isoureas and guanidine derivatives (Scheme 11).…”

An Unusual Oxidation of 1,5-Dimethyl-2,4-bis(dialkylamino)-1,5-diaza-2,4-diphosphinan-6-one with Hexafluoroacetone

“…[10] Owing to the n N(1,2) Ϫπ CϭO conjugation, the N(1)ϪC (2) and N(2)ϪC(2) bonds of 8b-cis and 7b-trans are noticeably shorter than the standard value of 1.45 Å for the N(sp 2 )ϪC(sp 2 ) single bond. [11] Comparison of the geometrical parameters of 8b-cis and 7b-trans with the corresponding values in related systems [10,12Ϫ14] shows delocalization of electron density over the N(1)ϪP(1)ϪC(1)ϪP(2)ϪN(2) bond system for the former molecules. It is noteworthy that unlike compound 7b-trans, in which the P(1)ϭC (1) For the further studies of the reactions of PϪCH 2 ϪP-containing heterocycles with HFA we used compound 9.…”