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 reaction of the 4,4-dialkylated 2-cyclohexenones 1 or 2 with a twofold excess of a secondary amine 3 affords the 2-amino-1,3-cyclohexadienes 4 and 5, respectively. Irradiation (λ ≧ 300 nm) of the morpholino derivative 4a yields a mixture of the isomeric 3-morpholino-6-methyl-1,3,5-heptatrienes 6 and 7, while 5 gives only one corresponding product 8. The reaction of enone 1 with an equimolar amount of pyrrolidine (3c) affords the bis-enamine 9 which is converted to the unsaturated diketone 10 by oxidative hydrolysis.

Synthesis and Photochemical Behaviour of 2-Amino-1,3-Cyclohexadienes

5,5-Dimethylcyclohex-2-enone (1a) photocycloadds to ethylidenemalononitrile (2a) to give 5-oxobicyclo[4.2.0]octane-7,7-dicarbonitriles with slight preference, in analogy to results already described for light induced reactions between cyclohexenones and acrylonitrile (AN). In contrast, irradiation of 1a in the presence of isopropylidenemalononitrile (2b) leads to selective formation of the (opposed) 2-oxo regioisomers. Similar trends in product distribution regarding the orientation of addition are also observed in light-induced reactions of 2-alkynylcyclohexenone 1b with either 2a or 2b.

/pdf/photocycloaddition-of-cyclohex-2-enones-to-xsuu3me63a.pdf

Photocycloaddition of cyclohex-2-enones to alkylidenemalononitriles (1,1-dicyanoalkenes).

2-Pivaloylcyclohex-2-enone 4, obtained from 2,2-dimethylcyclohexanone in three steps in 70% yield, is converted into tetrahydrobenzo[c]furan-4-one 6 on irradiation (254 nm) in propan-2-ol.

https://journals.sagepub.com/doi/pdf/10.1177/174751989902300317

Synthesis and Photoreactivity of a 2-Pivaloylcyclohex-2-enone

Photolyse von 2,3‐Diazido‐2,3‐dimethylbutan

Irradiation (350 nm) of 1-thiocoumarin in solution affords the title compound in 55% yield. This compound crystallizes in the chiral space group P6 5 with two molecules in the asymmetric unit. The absolute structure of the title compound was determined through the Flack parameter, x=0.00(2)[Flack (1983). Acta Cryst. A39, 876-881]. The experimental data are compared to those of the corresponding coumarin dimer. The cyclobutane ring of the title compound shows a puckered conformation. The fused six-membered thiopyran rings adopt conformations between half-chair (H conformation) and twist-boat (S conformation)

Paul Margaretha

Papers

Synthesis and Photochemical Behaviour of 2-Amino-1,3-Cyclohexadienes

Photocycloaddition of cyclohex-2-enones to alkylidenemalononitriles (1,1-dicyanoalkenes).

Synthesis and Photoreactivity of a 2-Pivaloylcyclohex-2-enone

Photolyse von 2,3‐Diazido‐2,3‐dimethylbutan

(6aα,6bβ,12bβ,12cα)-6a,6b,12b,12c-Tetrahydrocyclobuta [1,2-c:4,3-c'] di [1] benzothiopyran-6,7-dione