Palladium-catalyzed desulfinylative C–C allylation of Grignard reagents and enolates using allylsulfonyl chlorides and esters

Iodine-Catalyzed Synthesis of Substituted Furans and Pyrans: Reaction Scope and Mechanistic Insights

Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furans using molecular iodine, a simple and inexpensive catalyst. The method described is performed under solvent-free conditions at an ambient temperature and atmosphere, thus offering a facile and practical alternative to currently available reaction protocols. A combination of experimental studies and density functional theory calculations revealed interesting mechanistic insights into this seemingly simple reaction.

Transition metal-free synthesis of sterically hindered allylarenes from 5-hexene-2-one

A simple, efficient and transition metal-free strategy was established for the synthesis of highly functionalized, sterically hindered allylarenes (6, 7 & 8) by base-mediated ring transformation of 2-oxo-6-aryl-4-(methylthio/sec-amino)-2H-pyran-3-carbonitriles (3/4) with 5-hexene-2-one (5). This provides a method for the synthesis of allylarenes functionalized with different electron donating and withdrawing groups in one pot. The structures of isolated products 6c and 7a were ascertained by spectroscopic and single crystal X-ray diffraction analyses. In addition, we have performed a molecular docking study to predict the biological activity of the synthesized molecules for binding to estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ).

CuI catalyzed sulfonylation of organozinc reagents with sulfonyl halides

A general and efficient CuI/TMEDA catalyzed nucleophilic addition of functionalized organozinc reagents to organic sulfonyl chlorides has been developed for both aromatic and aliphatic sulfone synthesis.

Iron-catalyzed cross-coupling of unactivated secondary alkyl thio ethers and sulfones with aryl Grignard reagents

The first systematic investigation of unactivated aliphatic sulfur compounds as electrophiles in transition-metal-catalyzed cross-coupling are described. Initial studies focused on discerning the structural and electronic features of the organosulfur substrate that enable the challenging oxidative addition to the C(sp(3))-S bond. Through extensive optimization efforts, an Fe(acac)3-catalyzed cross-coupling of unactivated alkyl aryl thio ethers with aryl Grignard reagents was realized in which a nitrogen "directing group" on the S-aryl moiety of the thio ether served a critical role in facilitating the oxidative addition step. In addition, alkyl phenyl sulfones were found to be effective electrophiles in the Fe(acac)3-catalyzed cross-coupling with aryl Grignard reagents. For the latter class of electrophile, a thorough assessment of the various reaction parameters revealed a dramatic enhancement in reaction efficiency with an excess of TMEDA (8.0 equiv). The optimized reaction protocol was used to evaluate the scope of the method with respect to both the organomagnesium nucleophile and sulfone electrophile.

Selective cross-coupling of organic halides with allylic acetates

A general protocol for the coupling of haloarenes with a variety of allylic acetates is presented. Strengths of the method are a tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) substrates and the ability to couple with a variety of substituted allylic acetates. Secondary alkyl bromides can also be allylated under slightly modified conditions, demonstrating the generality of the approach. Finally, the coupling of a reactive vinyl halide could be achieved by the use of a very hindered ligand and more reactive, branched allylic acetates.