Straightforward access to tetrahydropyridine and piperidine-fused fluorolactones from pyridines and bis(trimethylsilyl)ketene acetals

Different routes for the construction of biologically active diversely functionalized bicyclo[3.3.1]nonanes: an exploration of new perspectives for anticancer chemotherapeutics

Cancer is the second most high-morbidity disease throughout the world. From ancient days, natural products have been known to possess several biological activities, and research on natural products is one of the most enticing areas where scientists are engrossed in the extraction of valuable compounds from various plants to isolate many life-saving medicines, along with their other applications. It has been noticed that the bicyclo[3.3.1]nonane moiety is predominant in most biologically active natural products owing to its exceptional characteristics compared to others. Many derivatives of bicyclo[3.3.1]nonane are attractive to researchers for use in asymmetric catalysis or as potent anticancer entities along with their successful applications as ion receptors, metallocycles, and molecular tweezers. Therefore, this review article discusses several miscellaneous synthetic routes for the construction of bicyclo[3.3.1]nonanes and their heteroanalogues in association with the delineation of their anticancer activities with few selective compounds.

Asymmetric organocatalyzed reaction sequence of 2-hydroxy cinnamaldehydes and acyclic N-sulfonyl ketimines to construct diverse chiral bridged polycyclic aminals

2-Hydroxy cinnamaldehydes and acyclic N-sulfonyl ketimines were used as multisite substrates in an iminium catalysis triggered sequential process, leading to diverse chiral bridged polycyclic aminals in a highly regio- and stereoselective manner.

Silver-catalyzed radical phosphonofluorination of unactivated alkenes

We report herein a mild and catalytic phosphonofluorination of unactivated alkenes. With catalysis by AgNO3, the condensation of various unactivated alkenes with diethyl phosphite and Selectfluor reagent in CH2Cl2/H2O/HOAc at 40 °C led to the efficient synthesis of β-fluorinated alkylphosphonates with good stereoselectivity and wide functional group compatibility. A mechanism involving silver-catalyzed oxidative generation of phosphonyl radicals and silver-assisted fluorine atom transfer is proposed.

Synthesis of new γ-lactones from preactivated monosubstituted pyrazines and TMS–ketene acetals

The double addition of bis(trimethylsilyl) ketene acetals (1a–1b, R1 = CH3, –(CH2)5–) to 2-substituted pyrazines promoted by triflic anhydride leads to γ-lactones in a single step. A systematic study involving electron-withdrawing and electron-donating groups (R2 = CN, COOMe, PhCH=CH, Cl, Me, OMe) in the pyrazine ring reveals a strong dependence of electronic effects on the regiochemistry of nucleophilic addition.