Synthesis of the entire carbon framework of the kedarcidin chromophore aglycon

In advanced studies directed toward the total synthesis of the kedarcidin chromophore, we have successfully achieved the late-stage installation of the nine-membered diyne ring in the presence of the highly functionalised ansamacrocyclic bridge

Efficient construction of the kedarcidin chromophore ansamacrolide

The streamlined assembly of the ansamacrolide framework of the kedarcidin chromophore via an efficient atropselective Sonogashira coupling step is described. To this end, two newly improved practical syntheses of the cyclopentene and dine fragments have been developed, which feature 0.2 mol % catalytic loadings for an RCM step and i-PrMgCl/CH2I2 as a new entry to gem-disubstituted epoxides from ketones, both being applicable to 49-g scales

A high triplet-energy polymer : synthesis and photo-physical properties of a pi-stacked vinyl polymer having a xanthone moiety in the side chain

Poly(xanthon-3-ylmethacrylate) (poly(XOMA))and poly(xanthon-3-yl methacrylate-co-methyl methacrylate) (poly(XOMA-co-MMA)) having a pi-stacked conformation were synthesized as host material candidates for phosphorescence-based light emitting diodes. Poly(XOMA) harvested photo excitation energy for blue phosphorescent emission of iridium bis[(4,6-difluorophenyl) pyridinato-N, C-2] picolinate (FIrpic) in a CHCl3 solution and in film

Catalyst-free click cascade functionalization of unsaturated-bond-containing polymers using masked-ketene-tethering nitrile N-oxide

We developed a facile protocol for grafting-onto and cross-linking unsaturated-bond-containing common polymers via the formation of masked-ketene-functionalized polymers. The protocol utilizes a cascade functionalization agent 1 that has nitrile N-oxide and masked ketene functionalities. Through the model ligation reactions using 1, it turned out that the 1 facilitates the catalyst-free click introduction of masked ketene moieties to the unsaturated bonds such as C equivalent to N and C=C bonds, capable of undergoing catalyst-free ligation with not only a nucleophilic amine but also a neutral alcohol with low nucleophilicity. On the basis of these results, the catalyst-free grafting reactions of PEG onto EPDM and PAN using 1 were performed to afford the corresponding graft copolymers in excellent conversion yields. In addition, it was also revealed that heating of both PAN and NR with masked ketene moieties at 250 degrees C for 1 h without catalyst enables the efficient conversion to give the respective cross-linked polymers. (c) 2013 Elsevier Ltd. All rights reserved

Gigantic chiroptical enhancements in polyfluorene copolymers bearing bulky neomenthyl groups : importance of alternating sequences of chiral and achiral fluorene units

An alternating copolymer consisting of achiral and chiral units emits remarkably efficient CPL on photo-excitation. The main-chain twist bias is enhanced by thermal annealing by the factor of 10(4) in the ground state. An anisotropy factor of the polymer in the excited state is greater by approximately an order of magnitude compared with that in the ground sate