Synthesis of Schiff Bases and Secondary Amines with Indane Skeleton; Evaluation of Their Antioxidant, Antibiotic, and Antifungal Activities.

In this study, Schiff bases were synthesized by utilizing the reaction of 4- and 5-aminoindane with substituted benzaldehydes. After the reduction of isolated Schiff bases with NaBH4 , the corresponding secondary amine derivatives were obtained. The structures of all synthesized molecules were confirmed by 1 H-NMR, 13 C-NMR, FT-IR, and ESI-MS. Antioxidant activities of all synthesized molecules were investigated by DPPH method, and IC50 values were calculated. In addition, antibacterial activities of targets were investigated by the well diffusion method, and then MIC99 values were calculated. While only four of the sixteen synthesized molecules showed a high level of antioxidant activity, all of the molecules exhibited biological activity against Gram-positive and Gram-negative bacteria to varying degrees. In addition, all the synthesized molecules showed high antifungal activity. In antioxidant capacity studies, the IC50 values of 2-(((2,3-dihydro-1H-inden-5-yl)amino)methyl)-6-methoxyphenol (4 d) and 2-(((2,3-dihydro-1H-inden-4-yl)amino)methyl)-6-methoxyphenol (7 d) were determined to be 18.1 µg and 35.1 µg, respectively, and these values are much stronger than BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole) used as positive controls. The fact that targets have the same core structure with different substituents has revealed a good structure-activity relationship.

Incorporation of an allene unit into alpha-pinene: generation of the cyclic allene 2,7,7-trimethylbicyclo[4.1.1]octa-2,3-diene and its dimerization.

The reaction of etheral methyllithium with 3,3-dibromo-2,7,7-trimethyl-tricyclo[4.1.1.0(2,4)]octane (2) was investigated. The generated carbene 12 undergoes intramolecular C-H insertion to provide the tetracyclic hydrocarbon 3 and the bicyclic allene 15, which undergoes [2+2] cyclodimerization. The structures of the formed allene dimers 16, 17, and 18 were elucidated by spectral means. The activation barriers for all possible C-H insertion products 3, 13, and 14 and the allene 15 were investigated by using density functional theory computations at the B3LYP/6-31G(d) level. It was found that the activation barriers for the formation of 3 and 15 (6.2 and 6.3 kcal mol(-1)) are much lower than that for the insertion products 13 and 14 (17.5 and 12.6 kcal mol(-1)), respectively. This prediction was completely in agreement with our experimental results.