TY - JOUR A1 - Schmidt, Bernd A1 - Riemer, Martin T1 - Synthesis of Allyl- and Prenylcoumarins via Microwave-Promoted Tandem Claisen Rearrangement/Wittig Olefination JF - Synthesis N2 - Allyl, dimethylallyl, crotyl, and prenyl ethers of various aromatic ortho-hydroxy carbonyl compounds undergo a tandem sequence of Claisen rearrangement, carbonyl olefination, and cyclization upon microwave irradiation in the presence of a stabilized ylide. The products are multiply substituted 6- or 8-allylated or prenylated coumarins (2H-chromen-2-ones). KW - aldehydes KW - coumarins KW - ketones KW - microwave irradiation KW - olefination KW - tandem reaction KW - ylides Y1 - 2016 U6 - https://doi.org/10.1055/s-0035-1560501 SN - 0039-7881 SN - 1437-210X VL - 48 SP - 141 EP - 149 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Nazir, Rashid A1 - Meiling, Till Thomas A1 - Cywinski, Piotr J. A1 - Gryko, Daniel T. T1 - Synthesis and Optical Properties of alpha,beta-Unsaturated Ketones Bearing a Benzofuran Moiety JF - Asian journal of organic chemistry : an ACES journal N2 - Five pi-expanded alpha,beta-unsaturated ketones have been prepared from a strongly electron-rich benzofuran derivative via Knoevenagel reaction and aldol condensation. The incorporation of two 6-didodecylaminobenzofuran-2-yl groups at the periphery of D-pi-A and D-pi-A-pi-D molecules resulted in dyes with excellent solubility in the majority of organic solvents. In contrast to the majority of alpha,beta-unsaturated ketones, these dyes emit relatively strongly in the red region with a fluorescence quantum yield up to 40%. They also display strong solvatofluorochromism with emission shifting from 570 nm in toluene to 670 nm in CHCl3. Depending on the chemical structure, they two-photon cross-sections (sigma(2)) are up to 1700 GM (1 GM=10(50) cm(4)s photon(-1)). KW - aldol reaction KW - benzofurans KW - fluorescence KW - ketones KW - two-photon absorption Y1 - 2015 U6 - https://doi.org/10.1002/ajoc.201500242 SN - 2193-5807 SN - 2193-5815 VL - 4 IS - 9 SP - 929 EP - 935 PB - Wiley-VCH CY - Weinheim ER -