Allenyl Sulfones and Allenyl Sulfides in the Synthesis of 3-Pyrrolines. A Novel Nucleophilic [3 + 2] Cycloaddition on Allenyl Sulfones Giving Rearranged Cycloadducts

CuI-Catalyzed Decarboxylative Thiolation of Propargylic Cyclic Carbonates/Carbamates to Access Allenyl Thioethers

The first CuI-catalyzed decarboxylative thiolation of terminal alkyne-substituted cyclic carbonates/carbamates to access allenes has been developed. A wide range of hydroxymethyl- and aminomethyl-containing allenyl thioethers were smoothly obtained in good to excellent yields under mild conditions. The copper-allenylidene intermediate among the process is crucial to the decarboxylative thiolation reaction. This method opens up a new channel to access allenyl thioether compounds.

Metal-Free C-C Coupling of an Allenyl Sulfone with Picolyl Amides to Access Vinyl Sulfones via Pyridine-Initiated In Situ Generation of Sulfinate Anion

Vinyl sulfones are privileged motifs known for their biological activity and synthetic utility. Synthetic transformations to efficiently access high-value compounds with these motifs are desired and sought after. Herein, a new procedure is described to form vinyl sulfone-containing compounds by selective functionalization of the C(sp³)-H bond adjacent to the pyridine ring of pharmacologically prevalent picolyl amides with an allenyl sulfone, 1-methyl-4-(propa-1,2-dien-1-ylsulfonyl)benzene. The reaction conditions are mild with no metal catalyst or additives required and display good functional group tolerance. Mechanistic studies for this unusual transformation suggest that the reaction operates via a rare pyridine-initiated and p-toluenesulfinate anion-mediated activation of the allenyl sulfone analogous to phosphine-triggered reactions.

Sulfur-directed palladium-catalyzed C(sp3)–H α-arylation of 3-pyrrolines: easy access to diverse polysubstituted pyrrolidines

A sulfur-directed palladium-catalyzed C(sp³)–H α-arylation of 3-pyrrolines with arylboronic acids has been disclosed, providing a range of 2-aryl-3-pyrolines, which could be readily converted to various polysubstituted pyrrolidines.

Synthetic and mechanistic aspects of sulfonyl migrations

Sulfonyl migrations, frequently described as ‘unusual’ or ‘unexpected’, from the last 20 years, including 1,2-, 1,3-, 1,4-, 1,5-, 1,6- and 1,7-sulfonyl shifts, through either radical or polar processes, either inter- or intramolecularly are reviewed.

Recent developments in the chemistry of allenyl sulfones

Allenyl sulfones are versatile building blocks for the construction of various acyclic, carbocyclic and heterocyclic motifs. Recent developments in the preparation and synthetic applications of allenyl sulfones are summarised.

Regiodivergent synthesis of 1- and 2-arylsulfonyl 1,3-dienes

In the course of a study of the alkoxyallylation of allenic sulfones through the use of π-allylpalladium chemistry, we discovered an isomerization of allenic sulfones to arylsulfonyl 1,3-dienes. Under conditions of palladium catalysis in the presence of acids such as acetic acid, allenic sulfones are converted to 1-arylsulfonyl 1,3-dienes. On the other hand, nucleophilic catalysis using triphenylphosphine in the presence of a proton shuttle yields 2-arylsulfonyl 1,3-dienes. Thus, either regioisomer of the arylsulfonyl diene can be prepared at will based on changes in reaction conditions.

Synthesis and biological evaluation of (2,5-dihydro-1H-pyrrol-1-yl)-2H-chromen-2-ones as free radical scavengers

The allylation of aminocoumarins in the presence of excess of anhydrous K(2)CO(3) and allyl bromide to diallylaminocoumarins is described. The Ring Closing Metathesis reaction of the later with the Grubbs' 1rst generation catalyst under reflux or MW irradiation has resulted mainly to (2,5-dihydro-1H-pyrrol-1-yl)coumarins and (1H-pyrrol-1-yl)coumarins. The new compounds were tested in vitro for their ability: (i) to interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical, (ii) to inhibit lipid peroxidation, (iii) to scavenge the superoxide anion, (iv) to inhibit the activity of soybean lipoxygenase LO and (v) to scavenge hydroxyl radicals. Most of them were found to be potent lipid peroxidation inhibitors in vitro. The majority of the compounds showed significant hydroxyl radical scavenging activity. Compounds 11a and 12c presenting higher LO inhibitory activity as well as compound 17 were found to present a promising antioxidant and LO inhibitory profile.