Design, synthesis, and SAR studies of novel polycyclic acids as potent and selective inhibitors of human 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1).

Bicyclo[2.2.l]hept-5-en-2-one was condensed with 2,2-dimethyl-1,3-dioxan-4,6-dione in the presence of titanium tetrachloride/pyridine to yield 5-(bicyclo[2.2.1]hept-5'-en-2'-ylidene)-2,2-dimethyl-1,3- dioxan-4,6-dione (6a) which on pyrolysis at 520-560o/0.01 mm gave acetone, carbon dioxide, cyclopentadiene and butatrienone. In the same way 5-(7'-oxabicyclo[2.2.1]hept-5'-en-2'-ylidene)-2,2- dimethyl-1,3-dioxan-4,6-dione (6b) was prepared from 7-oxabicyclo[2.2.1]hept-5-en-2-one and on pyrolysis at 570o/0.01 mm it gave acetone, carbon dioxide, furan and butatrienone. Alkylation of 2-trimethylsiloxybicyclo[2.2.1]hepta-2,5 with phenylthiomethyl chloride with titanium tetrachloride as catalyst followed by condensation with 2,2-dimethyl-1,3-dioxan-4,6-dione gave an endo/exo mixture of 5-(3'-phenylthiomethylbicyclo[2.2.1]hept-5'-en-2'-ylidene)-2,2-dimethy 1-1,3-dioxan- 4,6-dione. The structure of the endo isomer was established by X-ray crystallography. Oxidation of the phenylthiomethyl compound with m-chloroperbenzoic acid yielded the sulfoxide which was converted by boiling in carbon tetrachloride into 5-(3'-methylenebicyclo[2.2.l]hept-5'-en-2'-ylidene)- 2,2-dimethyl-1,3-dioxan-4,6-dione (8). Preliminary studies on the fragmentation of compound (8) have shown that at 450o/0.01 mm it is converted into acetone, carbon dioxide and products showing ketene absorption at 2140 cm-1. The formation of pentatetraenone has not been established with certainty. The 3'-phenylsulfonylmethyl, phenylselenyl and methyl derivatives of (6a) are also described.

Synthesis of precursors of c4 and c5 cumulenones

Covalent linker transformations in metal–organic frameworks (MOFs) enable their functionalization but often suffer from low conversions or require harsh conditions, including heating, corrosive reactants and solvents, or catalysts. In this work, using solvent-free mechanochemistry for the first time for such conversions, we demonstrate the systematic MOF pore modification with pendant hydroxyl groups and the resulting effects on the network rigidity, its luminescent properties, as well as adsorption of CO2 and vapors of methanol, ethanol, isopropanol, D2O, and H2O. A new zinc-based heterolinker MOF (JUK-20) containing both protic luminescent units and reactive tetrazine cores was used as a model and subjected to an inverse electron-demand Diels–Alder (iEDDA) click reaction with a series of dienophiles (x) of different lengths having OH groups. From the obtained series of JUK-20(Zn)-x MOFs, a flexible material capable of luminescent humidity sensing was identified, and the influence of water on the luminescence of the material was explained by analogy with the excited-state intramolecular proton transfer (ESIPT) model. In general, our results provide guidance for designing and tuning MOFs for luminescence-based detection using a stepwise synthetic approach.

https://pubs.acs.org/doi/pdf/10.1021/acsami.3c00788

Covalent Modification by Click Mechanochemistry: Systematic Installation of Pendant OH Groups in a MOF for Rigidity Control and Luminescence-Based Water Detection

Material dealing with methods for obtaining 1,3-dioxane-4,6-diones and their derivatives, methods for cleaving the 1,3-dioxane ring, and, within the framework of a synthone approach, trends in their utilization in organic synthesis is correlated.

https://link.springer.com/content/pdf/10.1007%2FBF00473985.pdf

M. Pfenninger

Papers

Synthesis of precursors of C4 and C5 cumulenones

Synthesis of precursors of c4 and c5 cumulenones