Nucleotides. Part 71. A New Type of Labelling of Nucleosides and Nucleotides.

Abstract

A new labelling technique attaching fluorescein via a carbamoyl linker directly to the amino groups of the nucleobases was developed. The amino groups were first converted to the phenoxycarbonyl derivatives ( 3 10, 15, 19, 58), which reacted under mild conditions with 5-aminofluorescein to give the corresponding N-[(fluorescein-5-ylamino)carbonyl] derivatives ( 3 11 ± 14, 16, 17, 20, 59, 60). The introduction of the 5-aminofluorescein residue into properly protected adenylyl-adenosine dimers ( 3 39, 40) and trimer ( 3 50) worked well, and final deprotection of these uniformly blocked precursors led on treatment with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), in one step to dimer 41 and trimer 51. Synthesis of an appropriately protected monomeric phosphoramidite building block ( 3 75) was more difficult, since introduction of the 2-(4-nitrophenyl)ethyl residue into the fluorescein moiety in 59 led mainly to trisubstitution to give 61 including the urea function. Formation of the adenylyl dimer 66 and trimer 67 proceeded in the usual manner by phosphoramidite chemistry; however, deprotection of 67 with DBU was incomplete since the O-alkyl group at the urea moiety was found to be very stable. Finally, the appropriate phosphoramidite building block 75 could be synthesized by the sequence 59 3 72 3 73 3 74 3 75. The phosphoramidite 75 was used for the synthesis of dimer 77 and trimer 79 by solution chemistry, as well as for that of various oligonucleotides by the machineaided approach on solid support carrying the fluorophore at different positions of the chain ( 3 84 ± 87). The attachment of the fluorescein fluorophor via a short carbamoyl linker onto the 6-amino group of 2'-deoxyadenosine enables such molecules to function very well in fluorescence-polarization experiments.

The garlic compound ajoene targets protein folding in the endoplasmic reticulum of cancer cells

“…Thermal condensation of 4‐nitrophthalic acid with resorcinol gave a mixture of regioisomeric 4‐ and 5‐nitrofluoresceins ( 9 ) (lactone carbonyl‐bearing carbon as C‐1) that could not be separated chromatographically or by fractional crystallization. For this a literature procedure was followed , which involved converting the mixture to the diacetates by refluxing in acetic anhydride and then subjecting the product to a fractional crystallization. Deprotection of the individual regioisomers with sodium hydroxide, followed by exposure to acetic acid to restore the lactone ring furnished crystalline 4‐ and 5‐isomers ( 9a and b ) in 18 and 17% yield, respectively (Figure Part B).…”

Peculiarities of the 4,5‐dinitrofluorescein esters synthesis: formation of reduced species

“…Crystals of 4 (C 26 H 24 N 2 O 9 , Mr = 508.48) were obtained by recrystallisation from 96% ethanol (see Synthesis, section 2.4). The crystals are monoclinic, C2/c, a = 32.874 (4) Å, b = 13.9734 (16) Å, c = 22.148 (3) Å, β = 90.145 (14) º, V = 10 174 (2) Å 3 , Z = 16, d calc = 1.328 g/cm 3 , μ = 0.102 mm −1 , F(000) = 4256.84504 reflections (13 875 independent, Rint = 0.339) were collected at 298 K on an Xcalibur-3 diffractometer ( MoKα radiation, chargecoupled device detector, graphite monochromator, ωscanning, 2θmax = 52°). The structure was solved by direct methods and refined against F 2 within anisotropic approximation for all non-hydrogen atoms by the fullmatrix least squares procedure using the OLEX2 program package 25 with the SHELXT and SHELXL modules.…”

“…The problem of synthesising esters of fluorescein dyes has long been solved for the mother compound [5][6][7][8][9][10] and its derivatives. [11][12][13][14][15][16][17] Typically, the esterification is carried out in methanol 6,7,10,14 or ethanol 5,15 in the presence of concentrated sulphuric acid. This procedure also works for nitro 14 and amino 14,15 derivatives of fluorescein with substituents in the phthalic acid residue.…”

“…[11][12][13][14][15][16][17] Typically, the esterification is carried out in methanol 6,7,10,14 or ethanol 5,15 in the presence of concentrated sulphuric acid. This procedure also works for nitro 14 and amino 14,15 derivatives of fluorescein with substituents in the phthalic acid residue. For the halogen derivatives such as eosin, erythrosin and rose Bengal B, the use of iodoalkyls or bromoalkyls in basic media is preferred.…”

Antiproliferative and Protein Kinase Binding Activities of Some N 6, 5′-bis-ureido 5′-Amino-5′-Deoxyadenosine Derivatives

“…[1][2][3][4][5][6][7] Various 3 -ureido derivatives have exhibited low-to submicromolar binding affinities for mutant human A 3 (AR) receptors, an effect not observed with wild type A 3 (AR), thus offering orthogonal and selective activation of the reengineered receptor via an organ-targeted "neoceptor" approach. [1] Select N 6 -ureido-purine and -adenosine derivatives were prepared as early as the 1970's as potential antiproliferative agents, [2] and the N 6 -carbamoyl moiety continues to be exploited as a versatile means of linking such useful functionalities to adenosine as fluorescent chromophores, [3] duplex stabilizing aryl groups, [4] (10 µM) initial screen are illustrated in Table 1. Compounds 2c and 2d were superior to lactones 2g and 2h in the single dose growth inhibition assay.…”