A concise synthesis of (-)-dihydrospirotryprostatin B via tandem Michael addition

Enantioselective formal total synthesis of dihydrospirotryprostatin B

Spirotryprostatins are representative members of medicinally interesting bioactive molecules of the spirooxindole natural products. In this communication, we present a novel enantioselective total synthesis of the spirooxindole alkaloid dihydrospirotryprostatin B. The synthesis takes advantage of copper-catalyzed tandem reaction of o-iodoanilide chiral sulfinamide derivatives with alkynone to rapidly construct the key quaternary carbon stereocenter of the natural product dihydrospirotryprostatin B.

Catalyzed syntheses of novel series of spiro thiazolidinone derivatives with nano Fe2O3: spectroscopic, X-ray, Hirshfeld surface, DFT, biological and docking evaluations

Twelve spiro thiazolidinone compounds (A-L) were synthesized via either conventional thermal or ultrasonication techniques using Fe2O3 nanoparticles. The modification of the traditional procedure by using Fe2O3 nanoparticles led to enhancement of the yield of the desired candidates to 78-93% in approximately half reaction time compared with 58-79% without catalyst. The products were fully characterized using different analytical and spectroscopic techniques. The structure of the two derivatives 4-phenyl-1-thia-4-azaspirodecan-3-one (A) and 4-(p-tolyl)-1-thia-4-azaspirodecan-3-one (B) were also determined using single crystal X-ray diffraction and Hirshfeld surface analysis. The two compounds (A and B) were crystallized in the orthorhombic system with Pbca and P212121 space groups, respectively. In addition, the crystal packing of compounds revealed the formation of supramolecular array with a net of intermolecular hydrogen bonding interactions. The energy optimized geometries of some selected derivatives were performed by density functional theory (DFT/B3LYP). The reactivity descriptors were also calculated and correlated with their biological properties. All the reported compounds were screened for antimicrobial inhibitions. The two derivatives, F and J, exhibited the highest levels of bacterial inhibition with an inhibition zone of 10-17 mm. Also, the two derivatives, F and J, displayed the most potent fungal inhibition with an inhibition zone of 15-23 mm. Molecular docking investigations of some selected derivatives were performed using a B-DNA (PDB: 1BNA) as a macromolecular target. Structure and activity relationship of the reported compounds were correlated with the data of antimicrobial activities and the computed reactivity parameters.

Antibacterial and Anticandidal Activity of the Nanostructural Composite of a Spirothiazolidine-Derivative Assembled on Silver Nanoparticles

Our aims in this work are the preparation of an ionic liquid based on heterocyclic compounds with Ag nanoparticles and the investigation of its application as an antibacterial and anticandidal agent. These goals were achieved through the fabrication of an ionic liquid based on Ag nanoparticles with 5-Amino-3-(4-fluorophenyl)-N-hexadecyl-7-(4-methylphenyl)-2-H spiro[cyclohexane1,2'-[1,3]thiazolo [4,5-b]pyridine]-6-carbonitrile (P16). The nanostructure of the prepared ionic liquid was characterized using techniques such as FTIR, 1HNMR, 13CNMR, UV, SEM, and TEM. The biological activity of the prepared compound (P16) and its nanocomposites with Ag nanoparticles was tested using five clinical bacteria (Pseudomonas aeruginosa 249; Escherichia coli 141; Enterobacter cloacae 235; Staphylococcus epidermidis BC 161, and methicillin-resistant S. aureus 217), and three Candida species (Candida utilis ATCC 9255; C. tropicalis ATCC 1362, and C. albicans ATCC 20402). The FTIR, 1HNMR, and 13CNMR results confirmed the chemical structure of the synthesized P16 compound. The nanostructure of the prepared ionic liquid was determined based on data obtained from the UV, SEM, and TEM tests. The antibacterial and anticandidal results showed that the biological activity of the compound (P16) was enhanced after the formation of nanocomposite structures with Ag nanoparticles. Moreover, the biological activity of the compound itself (P16) and that of its nanocomposite structure with Ag nanoparticles was higher than that of ampicillin and amphotericin B, which were used as control drugs in this work.

Enantioselective Total Synthesis of Spirotryprostatin A

In this paper, we disclosed a novel enantioselective total synthesis of spirotryprostatin A (1) in 15 steps with a 7.4% total yield from commercially available 2-iodo-5-methoxyaniline and γ-butyrolactone. The key step features of this synthesis include the copper-catalyzed cascade reaction of o-iodoaniline derivatives with alkynone to introduce the quaternary carbon stereocenter and an aza-Michael tandem reaction to construct the spiro[pyrrolidine-3,3'-oxindole] moiety.