2,5‐Diazapentalenes

Abstract

each other is reduced. Indeed, a reduced sliding ability of the molecules, dependent on T,,, and thus an increase in intermolecular cross-linkage is demonstrated by the delayed increase in [?/Ii shown in Figure 2.

Diketopyrrolopyrroles: Synthesis, Reactivity, and Optical Properties

“…Gompper and co-workers proposed a method consisting of heating the succinic acid diamide with N , N -dimethylbenzamide diethyl acetal ( 36 , Scheme 18 ). [ 24 ] Two products can be obtained by this reaction: DPP 2 (30% yield) and compound 37 , the latter of which can be quantitatively converted to DPP 2 by the action of potassium tert -butoxide (overall yield of DPP: ∼60%). The analogous reaction of succinic amide with tetramethylurea acetal 38 leads to the product 39 , which is a non-conjugated tautomer of DPP (Scheme 18 ).…”

“…DPPs react with thiation reagents, such as phosphorus pentasulfi de (P 4 S 10 ) and Lawesson's reagent (LR), to give blue-green dithioketopyrrolopyrroles 62 with a good yield ( Scheme 27 ). [ 24,40 ] By this method, DPP 2 was converted to dithiolactam 62a , a compound existing in several polymorphic crystalline forms. The photophysical and electronic properties of these forms were thoroughly studied, mainly by Mizuguchi and co-workers.…”

“…[ 24a , 40 , 42 ] In contrast to DPPs, which undergo predominantly N -alkylation, the sulfur analogues 62 react with alkyl halides under basic conditions to give S , S -dialkylated compounds of type 63 as the main products. [ 24,33,43 ] This is presumably an effect of the higher nucleophilicity of sulfur atoms than either nitrogen or oxygen atoms. The alkylation of dithiolactams 62 together with O -silylation of DPP, described in the previous section, are two of the fi rst known methods for the synthesis of 2,5-diazapentalene derivatives ( 55 , Scheme 23 ).…”

Microwave-assisted rapid synthesis of 1,4-diketo-pyrrolo[3,4-]-pyrroles' derivatives under solvent-free conditions

“…Another synthetic modification of the succinic acid principle was found by Closs and Gompper in the reaction of succindiamide with N,N-dimethylbenzamide diethyl acetal [7].…”

Synthesis of diketopyrrolopyrrole (DPP) derivatives comprising bithiophene moieties

“…These heterocyclic compounds have been the object of several crystallographic studies and it was shown that the solidstate arrangement of DPP molecules occurs in parallel sheets. [6][7][8][9] The colour derives not only from the molecular structure, but also from the supramolecular order (p-p-interactions between the layer of molecules), since the colour in solid state differs from the colour in very dilute solutions. 10 The hydrogen bonding between neighbouring lactam-nitrogen and carbonyl-oxygen atoms is crucial for pigments in order to limit solubility.…”