Synthesis azobenzene derivatives

Organic synthesis 38 [OS 38] Formation of an azobenzene derivative from N,N-dimethylaniline with 4-nitrobenzenediazonium tetrafluoroborate... 

The synthesis of N,N-dimethylaniline with 4-nitrobenzenediazonium tetrafluoroborate yielded the corresponding azobenzene derivative [107] (see also [14]). 

Organic synthesis 39 [OS 39) Formation of azobenzene derivatives for pigment production... 

Aoyagi, T. Ueno, A. Fukushima, M. and Osa, T. (1998) Synthesis and photoisomerization of an azobenzene derivative bearing two (i-cyclodextrin units at both ends, Macromol. Rapid Commun. 19, 103-105. 

Park. S.B., and Standaert. R.R. a,a-Difluorophosphonomethyl azobenzene derivatives as photo-regulated phosphoamino acid analogs. Part 1. Design and synthesis. Tetrahedron Lett.. 40. 6557, 1999. 

Sanpei H. 2005. Studies on design and synthesis of chiral azobenzene derivatives, Master Thesis. Kumamoto University, Kumamoto, Japan. 

Two synthetic methods have been exploited to incorporate azobenzene moieties into mesoporous silica frameworks. The postgrafting method involves functionalizing mesoporous sol-gel materials with reactive azobenzene derivatives to tether azobenzene moieties to sol-gel matrices. The one-pot synthesis method requires... 

Despite the seminal findings of Murahashi, cobalt had been rarely used in catalytic C-H functionalization. With respect to heterocycle synthesis, a notable example known before the late 2000s would be the reaction of an azobenzene derivative with diphenylacetylene reported by Kisch and coworkers in 1994 (Scheme 10.2) [5]. In the presence of a cobalt complex CoH(N2)(PPh3)3 or CofHlgfPPhglg, both of the ortho C-H bonds of the azobenzene derivative undergo insertion of a diphenylacetylene molecule, affording a simple dialkeny-lated product or its annulated product, that is, a dihydrocinnoline derivative, depending on the substituents. 

The reaction of o-nitrobenzaldehydes with some benzene derivatives in the presence of strong acid (H2S04, PPA) is a classical synthesis of acridinol N-oxides (373) (37BSF240) The synthesis works for benzyl alcohol, benzene, toluene and halobenzenes, but not for benzoic acid, benzonitrile, dimethylaniline, or nitrobenzene. Isoquinoline N-oxides (374) have been obtained from o-bromobenzaldoxime or the acetophenone derivative, and active methylene compounds with copper bromide and sodium hydride (77S760). The azobenzene cobalt tricarbonyl (375) reacts with hexafluorobut-2-yne to give a quinol-2-one (72CC1228), and the 3,4,5-tricyanopyridine (376) is formed when tetracyanoethylene reacts with an enaminonitrile (80S471). 

Photocyclisation - A wide variety of ring-forming reactions has again been reported. Irradiation of azepine derivative (16) results in 4-n-electrocyclisation to a mixture of the corresponding exo and endo cyclobutenes.6-Ti-Electrocyclisa-tion has been employed in a scaled-up synthesis (>300g) of 6-aza-l,10-phenan-throic anhydride (18) from the stilbazole (17). f-Azobenzene, incorporated into water-swollen acid-form Nafion fluorocarbon membranes, exists as the proto-nated form (19) and exhibits ambient temperature fluorescence, previously... 

Synthesis, under microwave irradiation conditions, of polyamides containing azobenzene units and hydantoin derivatives in the main chains has recently been proposed by Faghihi et al. [55]. Polycondensation of 4,4 -azodibenzoyl chloride with eight 5,5-disubstituted hydantoin moieties has been achieved in the presence of a small amount of o-cresol (Scheme 14.26). The polycondensations were performed in 8 min, in a domestic microwave oven, in a porcelain dish in which 1.0 mmol diacid chloride was mixed with an equimolar amount of diol in the presence of small amounts of o-cresol. The polymerization proceeded rapidly, compared with the bulk reactions under conventional conditions (8 min compared with 1 h), producing a series of polyamides in high yield and inherent viscosity between 0.35 to 0.60 dL g h... 

Photochromic LC polymers are usually synthesized via the copolymerization of mesogenic monomers with photochromic mesogenic or nonmesogenic monomers similar to the synthesis of chiral LC polymers (Figure 19), hut, instead of a chiral monomer, a photochromic monomer is used as a mle, its concentration varies from 10 to 60mol.%. Diverse derivatives of azobenzene, spiropyran, diarylethenes, dnnamates, and coumarin-containing derivatives are used as photoactive fragments. 

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