Abstract A boron trifluoride catalysed reaction of coplanar 9-(phenyl­ethynyl)-9H-fluoren-9-ols with various 2-aminobenzamides affords a number highly functionalized, conjugated (Z)-2-((2-(9H-fluoren-9-ylidene)-1-phenylethylidene)amino) benzamides in excellent yield. The the presence N-bromosuccinimide (E)-5-bromo-2-((2-bromo-2-(9H-fluoren-9-ylidene)-1-phenylethylidene)amino)benz­amides very go...

A conjugate from the YIGSR peptide and chitosan has been prepared on the basis of a regioselective modification strategy of chitosan, and its antimetastatic activity has been assayed. Chitosan was converted to its organosoluble derivative, 6-O-trityl-chitosan, in 3 steps, and then coupled with the peptide portion containing a spacer amino acid, Ac-Tyr-Ile-Gly-Ser-Arg-beta Ala-OH [beta Ala; beta...

The six-step synthesis of the di-triethylammonium salt of 5[prime]-O -trityl-6-N-pivaloyladenosine-2[prime]-(H -phosphonate)-3'-[(2-chlorophenyl) phosphate]9 from 3', 5'- O -(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-6-N-pivaloyla denosine1in 68% overall yield is described. Compound9is converted into a branched pentaribonucleoside tetraphosphate 24 and a branched cyclic pentaribonucleotide ('la...

We report our recent efforts directed at improving high-field DNP experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε = 25 to 82 that demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei including 13C, 2H, and 17O using trityl via the cross effect. We discuss a variety of sample p...

SnBr(4)-promoted oxonium-Prins cyclizations to form 2,3-disubstituted tetrahydrofurans (THFs) are reported. In the absence of an internal nucleophile, the carbocation intermediates are trapped by bromide to give 2,3-cis- and 2,3-trans-configured products; two variations with intramolecular trapping are also reported. One of these allows a single-step stereocontrolled synthesis of the core 2,3-c...

Fecapentaene-14 and -12 are directly acting mutagens that do not require metabolic activation. Their unusual structure suggests a possible mechanism of action. A carbocation that is formed by the addition of an electrophilic species (such as a proton) to the enol ether is most probably the reactive species. A series of model enol ethers with conjugated systems of various lengths was prepared, a...