Visible light-promoted C–H functionalization of ethers and electron-deficient arenes

Photocatalyst-free visible-light-mediated C–H arylation of ethers via C(Sp2)–C(Sp3) C–H functionalization involving hydrogen atom transfer (HAT) pathway.</p

Synthesis of Bifacial Peptide Nucleic Acids with Diketopiperazine Backbones

AbstractWe report a synthesis of bifacial peptide nucleic acids (bPNAs) with novel diketopiperazine (DKP) backbones that display unnatural melamine (M) bases, as well as native bases. To examine the structure–function scope of DKP bPNAs, we synthesized a set of bPNAs by using diaminopropionic acid, diaminobutyric acid, ornithine, and lysine derivatives to display the base-tripling motifs, which result in one, two, three, or four carbons linking the alpha carbon to the side-chain amine. Thermal denaturation of DNA hybrids with these bPNAs revealed that the optimal side-chain linkage was four carbons, corresponding to the lysine derivative. Accordingly, monomers displaying two bases per side-chain were prepared through double reductive alkylation of the ε-amine of Fmoc-lysine with acetaldehyde derivatives of adenine, cytidine, uridine, and melamine. With these building blocks in hand, DKP bPNAs were prepared to display a combination of native and synthetic (melamine) bases. Preliminary melting studies indicate binding signatures of cytidine- and melamine-displaying bPNAs to T-rich DNAs of noncanonical structure, though full characterization of this behavior is ongoing. The convenient and potentially scalable method described enables rapid access to DNA-binding scaffolds of low (&lt;1 kD) molecular weight and previously established cell permeability. We expect that this straightforward and efficient approach to nucleic acid binders will enable studies on noncanonical nucleic acid hybridization.</jats:p

Radical–radical cross coupling reactions of photo-excited fluorenones

Radical–radical cross coupling reactions of photoexcited 9-fluorenones have been accomplished for the first time, leading to the synthesis of 9-alkyl, pyrollidinyl and spiro-THF derivatives of 9-fluorenones.</p

Metal free access to quinolines via C–C bond cleavage of styrenes

A new metal free self-sorting tandem reaction between styrenes and anilines to access 2,4-disubstituted quinolines, involving simultaneous C–C and C–N bond formation along with a C–C bond cleavage, has been developed.</p

C–H functionalization of terminal alkynes towards stereospecific synthesis of (E) or (Z) 2-methylthio-1,4-ene-diones

An efficient metal free self-sorting tandem protocol for stereospecific synthesis of (E) or (Z) 2-methylthio-1,4-ene-diones has been developed.</p

A general metal free approach to α-ketoamides via oxidative amidation–diketonization of terminal alkynes

A metal free catalytic system employing TMSOTf/I2/DMSO for the oxidative amidation–diketonization of terminal alkynes, in order to produce a wide variety of α-ketoamides, has been developed.</p

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

A novel metal-free strategy for a rapid and α-selctive C-alkynylation of glycals was developed. The reaction utilizes TMSOTf as a promoter to generate in situ trimethylsilylacetylene for C-alkynylation. Thanks to this methodology, we can access C-glycosides in a single step from a variety of acetylenes , i.e., arylacetylenes and most importantly aliphatic alkynes