Long-chain acyloins and vicinal diketones

Abstract

Several methods for the preparation of long-chain vicinal diketones are examined. The acyloin condensation, followed by oxidation, provides an excellent route to symmetrical compounds but is not satisfactoryfor unsymmetrical diketones. The latter are prepared (i) from dialkylacetylenes by semihydrogenation, hydroxylation, and oxidation with aqueous N-bromosuccinimide ; and (ii) from an a-acetoxy-acid chloride and the sodio-derivative of a bistetrahydropyranyl or dibenzyl alkylmalonate, followed by removal of the protecting groups and decarboxylation to give the a-acetoxy-ketone, which is then hydrolysed and oxidised.W. Rigby, J . Chem. SOC., 1951, 793.

Poly(2,3-dihexylthieno[3,4-b]pyrazine-alt-2,3-dihexylquinoxaline): Processible, Low-Bandgap, Ambipolar-Acceptor Frameworks via Direct Arylation Polymerization

“…Although long-chain 2,3-dialkylquinoxalines have been reported, 32,33 such reports are sparse, and these species have found little application in conjugated materials. [34][35][36][37] This lack of dialkyl derivatives has been attributed at least in part to difficulties in producing the required alkyl-functionalized -diones, 33 whose syntheses are more difficult than the analogous diaryl species.…”