An efficient, green, and facile four-component reaction for the preparation of pyrano [2,3-c]pyrazole derivatives through the condensation reaction of aryl aldehydes, ethyl acetoacetate, malononitrile, and hydrazine hydrate or phenyl hydrazine in the presence of commercially available organocatalyst sodium benzoate under aqueous condition is reported. The products are produced with high yields and in shorter reaction times. It also is mild, safe, green and environmental friendly.

A variety of 4H-chromenes, benzochromenes, 4,5-dihydropyrano[3,2-c]chromenes, 4H-pyran-3-carboxylates, and 3,4-disubstituted isoxazol-5(4H)-ones have been synthesized in high yields by using potassium hydrogen phthalate (KHP) as an inexpensive, commercially available catalyst. It was found that the threecomponent tandem reaction enabled synthesis of pyran-annulated heterocycles in water at 50°C. 3,4-Disubstituted isoxazol-5(4H)-ones were synthesized by use of 10 mol% KHP in water at room temperature. Also, treatment of methylene-containing compounds (malononitrile or ethyl cyanoacetate) with aromatic aldehydes in the presence of 5 mol% KHP resulted in a,b-unsaturated nitriles. The procedure is an easily performed, straightforward method for synthesis of a variety of pyranannulated compounds, isoxazol-5(4H)-one-containing heterocycles, and Knoevenagel adducts. The reaction is safe, uses mild conditions, and is environmentally benign. Other notable advantages are reuse of the catalyst, no use of hazardous organic solvents, and ease of work-up.

The one-pot three-component reaction of aryl aldehydes with hydroxylamine hydrochloride and ethyl 3-oxobutanoate/ethyl 4-chloro-3-oxobutanoate/ ethyl 3-oxo-3-phenylpropanoate in the presence of boric acid, H 3 BO 3 , in water leads to 4H-isoxazol-5(4H)-ones in high yields. The merits of this method are efficiency, simplicity, clean, green, easy work-up, high yields, and shorter reaction times.

The facile synthesis of several 1,3‐diazabicyclo[3.1.0]hex‐3‐ene derivatives with varying substitutions such as 2‐methyl‐6‐(4‐nitrophenyl)‐2,4‐diphenyl‐(1), 2‐methyl‐6‐(4‐nitrophenyl)‐4‐phenyl‐2‐(pyridin‐3‐yl)‐(2), 2‐(furan‐2‐yl)‐6‐(4‐nitrophenyl)‐4‐phenyl‐(3), 2‐(furan‐2‐yl)‐6‐(3‐nitrophenyl)‐4‐phenyl‐(4), 6‐(3‐nitrophenyl)‐2,4‐diphenyl‐(5) and 6‐(4‐chlorophenyl)‐4‐(3‐nitrophenyl)‐2‐phenyl‐(6) that all behave as “intelligent materials” are reported.

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Photochromic compounds (1-6) are synthesized and characterized and the results of their spectra are presented. The structure-photochromic behavior relationship (SPBR) of the synthesized compounds has been analyzed. H. KIYANI ET AL. 560 Scheme 1. Scheme 2. Synthetic route for the preparation of bis compounds 1-6 Scheme 3. Synthetic route for the preparation of aziridines Scheme 4. Photochromic reactions of 1,3-diazabicyclo [3,1,0]hex-3-ene with phenylene or arylen linkage H NMR (500 MHz, CDCl 3 , ppm):d 2.09-2.12 (m, 4H), 2.53 (s, 2H), 3.54 (s, 2H), 4.03-4.16 (m, 4H), 6.83-6.89 (m, 4H), 6.93 (s, 2H), 7.02 (d, J ¼ 8.8 Hz, 2H), 7.16-7.21 (m, 4H), 7.25 (d, J ¼ 8.6 Hz, 4H), 7.37-7.43 (m, 8H), 7.93 (d, J ¼ 8.5 Hz, 4H), 8.03 (d, J ¼ 8.4 Hz, 4H); after irradiation with UV light converted to blue (open-form, 40%): 1 H NMR (500 MHz, CDCl 3 , ppm): d 1.96-2.03 (m, 4H), 2.55 (s, 2H), 3.56 (s, 2H), 4.03-4.16 (m, 4H), 6.3 (s, 2H), 6.83-6.89 (m, 4H), 7.00 (d, J ¼ 7.5 Hz, 2H), 7.16-7.21 (m, 4H), 7.25 (d, J ¼ 8.6 Hz, 4H), 7.37-7.43 (m, 8H), 7.93 (d, J ¼ 8.5 Hz, 4H), 7.98 (d, J ¼ 8.5 Hz, 4H). Anal. Calcd for C 48 H

Several 1,3-diazabicyclo[3,1,0]hex-3-ene derivatives with varying substitutions such as 9H-fluorenyl, 4-(cyclohexyl-phenyl)-2-methyl, 4-cyclohexyl phenyl, 2-phenyl-2-methyl, and 2-cyclohexyl-2-phenyl that behave as ‘intelligent material’ are reported.