3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20874-922.pdf

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

Palladium-catalyzed alkynylation.

The [2 + 2] photocycloaddition is undisputedly the most important and most frequently used photochemical reaction. In this review, it is attempted to cover all recent aspects of [2 + 2] photocycloaddition chemistry with an emphasis on synthetically relevant, regio-, and stereoselective reactions. The review aims to comprehensively discuss relevant work, which was done in the field in the last 20 years (i.e., from 1995 to 2015). Organization of the data follows a subdivision according to mechanism and substrate classes. Cu(I) and PET (photoinduced electron transfer) catalysis are treated separately in sections 2 and 4, whereas the vast majority of photocycloaddition reactions which occur by direct excitation or sensitization are divided within section 3 into individual subsections according to the photochemically excited olefin.

http://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.5b00723

Recent Advances in the Synthesis of Cyclobutanes by Olefin [2+2] Photocycloaddition Reactions

This paper reviews the tools to manipulate and minimize the band gap of conjugated (co)polymers. The effects of minimization of the bond length alternation and of the incorporation of donor-π-acceptor units are discussed in particular. A systematic study of a series of alternating donor–acceptor oligomers has revealed the achievable limits and allowed for a prognosis of the performance of corresponding copolymers. The decisive influence of the LUMO eigenvectors of the acceptors on the band gap is highlighted. A new synthesis of benzo[1,2-c:4,5-c]bis[1,2,5]thiadiazole containing donor–acceptor monomers and their acid-catalyzed polymerization are described. Finally, band gap tuning by appropriate substitution, conformational adjustment and mesoscopic ordering is discussed.

Developments in the chemistry and band gap engineering of donor-acceptor substituted conjugated polymers

Stereocontrolled synthesis of tetrasubstituted olefins.

The photochemical behaviour of the title compound, newly synthesized in four steps from 4,4-dimethylcyclohexanone, is compared to that of 4,4-dimethyl- and 4,4,6-trimethyl-2-cyclohexenone. All three enones undergo rearrangement to bicyclo[3.1.0]hexan-2-ones and 3-isopropyl-2-cyclopentenones in benzene, t.butanol and acentonitrile, but only the CF 3 -enone is also reduced to the saturated ketone in the latter two solvents.

Photochemistry of 6-Trifluoromethyl-4,4-dimethyl-2-cyclohexenone.

The photochemical behaviour of the title compound, newly synthesized from 2-trifluoromethylcyclohexanone by a bromination/dehydrobromination sequence, is compared to that of 6-methyl-2-cyclohexenone. Both compounds behave similarly regarding photocyclodimerization and addition to 2-methylpropene. Higher yields of reduction (electron transfer) products from the trifluorometahyl- vs. the methyl enone are obtained in the irradiations in the presence of 2,3-dimethyl-2-butene or in 2-propanol, respectively.

Paul Margaretha

Papers

Photochemistry of 6-Trifluoromethyl-4,4-dimethyl-2-cyclohexenone.

Photochemistry of 6-Trifluoromethyl-2-cyclohexenone.

Furans from Novel (3 + 2) Photocycloaddition of Alkenes to 2‐(1‐ Alkynyl)cyclohexenones.

Organische lewis-saeuren 26. mitt. hydrolytische spaltung der c=c-doppelbindung von organischen lewis-saeuren (i)

Influence of the water content of the solvent on the product distribution in the electrohydrodimerization of 2-cyclohexenones