Synthesis of Conformationally Locked Versions of Puromycin Analogues

Abstract

Conformationally locked North and South versions of puromycin analogues built on a bicyclo[3.1.0] hexane pseudosugar template were synthesized. The final assembly of the products was accomplished by the Staudinger-Vilarrasa coupling of the corresponding North (2 and 3) and South (6 and 7) 3′-azidopurine carbanucleosides with the Fmoc-protected 1-hydroxybenzotriazole ester of 4-methoxy-L-tyrosine. North azides 2 and 3 were reported earlier. The 3′-azido intermediates 6 and 7 that are necessary for the synthesis of the South puromycin analogues are described herein for the first time.Puromycin (1) is a 3′-amino-3′-deoxynucleoside antibiotic produced by Streptomyces alboniger 1 that specifically inhibits peptidyl transfer on both prokaryotic and eukaryotic ribosomes by interfering with RNA function and leading to premature chain termination during translation. 2,3 Like the natural substrate, but independent of the codon, it enters the A site because of its molecular resemblance to the 3′ end of the normal ester-linked 3′-aminoacyl tRNA. Its primary amino group is capable of taking over the nascent peptide chain; however, the resulting more stable amide bond is resistant to further nucleophilic attack. This causes the ribosome to stop peptide chain elongation and to release a truncated C-terminal puromycyl peptide, which may be lethal to the organism.

Total Syntheses of a Conformationally Locked North‐Type Methanocarba Puromycin Analogue and a Dinucleotide Derivative

“…Unlike the well-resolved 1 H NMR doublets for OCH 2 Ph in 26 and 27, the corresponding methylene 1 H resonance in 28 was broad, due to a geminal quadrupole 14 NC 1 H 2 Ph coupling. This methylene carbon signal could not be found either in 13 C NMR or in DEPT spectra, again most probably due to an efficient quadrupole 14 N 13 CH 2 Ph broadening. With the help of a clear 1 H-13 C HSQC cross-peak this 13 C atom was found to resonate at~44 ppm, which was confirmed by HMBC through a weak vicinal coupling between 13 CH 2 at 44 ppm and the ortho-1 H in the phenyl group (see Supporting Information).…”

“…[30] The N 6 -protected azido diol 32 was chemoselectively [31] coupled to the N-protected l-amino acid oxybenzotriazolyl ester Fmoc-Tyr(Me)-OBt (prepared in situ) by a Staudinger-Vilarrasa procedure, the conditions of which (reduction with Me 3 P, facile separation of Me 3 PO) had been optimized previously. [13,15] The coupled product 33 was completely deprotected by treatment with ethanolic MeNH 2 , to furnish target compound 2. A final lyophilization from H 2 O/TFA at pH 2.2 led to the more water-soluble 2·TFA salt as a white, fluffy solid.…”

“…The following key steps were utilized, the last five of which were elaborated during the synthesis along with a few nonevident protection/deprotection protocols: ring-opening Wittig reaction, Swern oxidation (stereodestructive), vinyl Grignard addition (stereoselective), ring-closing metathesis, chromo-oxidative rearrangement (stereodestructive), Luche reduction (stereoselective and regioselective), Simmons-Smith cyclopropanation (stereoselective), Mitsunobu coupling (stereoselective), Mattocks bromoacetylation (stereoselective and regioselective), two nucleophilic substitutions with acetate (regioselective) and azide (stereoselective), two Staudinger-Vilarrasa (chemoselective) amino acid couplings, and a nucleosidyl phosphoramidite coupling (chemoselective). Both analogues, together with several others, [13,31,34] are being tested in an in vitro assay for ribosome-catalyzed peptidyl transfer and the findings are being compared with enzymological results obtained with natural puromycin and natural A site substrates (i.e., 3'-aminoacyl transfer RNAs).…”

“…), DRX(300 MHz), and DRX (500 MHz) spectrometers.1 H NMR (300 and 500 MHz),13 C NMR (75 and 125 MHz, recorded with complete proton decoupling), and31 P NMR (121.5 MHz, recorded with complete proton decoupling) spectra were obtained with samples dissolved in CDCl 3 , CD3 OD, or [D 6 ]DMSO, with the residual solvent signals as internal references: 7.26 ppm for CHCl 3 , 3.31 ppm for CD 2 HOD, 2.50 ppm for (CD3)A C H T U N G T R E N N U N G (CD 2 H)S(O) for 1 H NMR experiments, and 77.0 ppm for CDCl 3 , 49.0 ppm for CD 3 OD, 39.4 ppm for (CD 3 ) 2 S(O) for 13 C NMR experiments. 31 P NMR experiments were referenced to H 3 PO 4 as an external standard (0.00 ppm).…”

Characterization of 2‐Fluoro‐2’‐deoxyadenosine in Duplex, G‐Quadruplex and i‐Motif

“…of N,Ndibutylformamide dimethyl acetal was added, which was synthesized following previous reports. [35,57] After stirring at room temper-ature for 1 h, the mixture got transparent. After evaporation, the crude residue was purified by column chromatography with CH 2 Cl 2 : MeOH = 15 : 1 (94 %).…”