1. Synthesis of novel uracil non-nucleoside derivatives as potential reverse transcriptase inhibitors of HIV-1
Nasser R El-Brollosy, Omar A Al-Deeb, Ali A El-Emam, Erik B Pedersen, Paolo La Colla, Gabriella Collu, Giuseppina Sanna, Roberta Loddo Arch Pharm (Weinheim). 2009 Nov;342(11):663-70. doi: 10.1002/ardp.200900139.
Novel emivirine and TNK-651 analogues 5a-d were synthesized by reaction of chloromethyl ethyl ether and / or benzyl chloromethyl ether, respectively, with uracils having 5-ethyl and 6-(4-methylbenzyl) or 6-(3,4-dimethoxybenzyl) substituents. A series of new uracil non-nucleosides substituted at N-1 with cyclopropylmethyloxymethyl 9a-d, 2-phenylethyloxymethyl 9e-h, and 3-phenylprop-1-yloxymethyl 9i-l were prepared on treatment of the corresponding uracils with the appropriate acetals 8a-c. Some of the tested compounds showed good activity against HIV-1 wild type. Among them, 1-cyclopropylmethyloxymethyl-5-ethyl-6-(3,5-dimethylbenzyl)uracil 9c and 5-ethyl-6-(3,5-dimethylbenzyl)-1-(2-phenylethyloxymethyl)uracil 9g showed inhibitory potency equally to emivirine against HIV-1 wild type. Furthermore, compounds 9c and 9g showed marginal better activity against NNRTI resistant mutants than emivirine.
2. Polymer-Assisted Biocatalysis: Effects of Macromolecular Architectures on the Stability and Catalytic Activity of Immobilized Enzymes toward Water-Soluble and Water-Insoluble Substrates
Dieter M Scheibel, Ivan Gitsov ACS Omega. 2018 Feb 28;3(2):1700-1709. doi: 10.1021/acsomega.7b01721. Epub 2018 Feb 9.
The aim of this study is to develop efficient enzyme immobilization media that will enable the reuse of the biocatalysts over multiple cycles, increase their thermal stability, and attenuate their activity toward hydrophobic substrates for "green" transformations in aqueous media. For this purpose, amphiphilic AB and ABA block copolymers were synthesized and tested with laccase (a multicopper oxidase). In all cases, the hydrophilic B block consisted of poly(ethylene glycol), PEG, with molecular masses of 3, 5, 13, 20, or 13 kDa poly(ethylene oxide). The hydrophobic A blocks were made of linear poly(styrene), PS; hyperbranched poly(p-chloromethyl styrene); or dendritic poly(benzyl ether)s of generations 2, 3, and 4 (G2, G3, and G4) with molecular masses ranging from 1 to 24 kDa. A total of 23 different copolymers (self-assembling into micelles or physical networks) were evaluated. Notable activity enhancements were achieved with both micelles (up to 253%) and hydrogels (up to 408%). The highest enzymatic activity and thermal stability were observed with laccase immobilized in hydrogels consisting of the linear ABA block copolymer PS2.7k-PEG3k-PS2.7k (13 290 μkat/L, 65 °C, ABTS test). This represents a 1245% improvement over native laccase at the same conditions. At 25 °C, the same complex showed a 1236% higher activity than the enzyme. The highest polymerization yield for a water-insoluble monomer was achieved with laccase immobilized in hydrogels composed of linear-dendritic ABA copolymer G3-PEG5k-G3 (85.5%, 45 °C, tyrosine monomer). The broad substrate specificity and reusability of the immobilized laccase were also demonstrated by the successful discoloration of bromophenol blue, methyl orange, and rhodamine B over eight repetitive cycles.
3. Electrophilic Aromatic Substitution. 13.(1) Kinetics and Spectroscopy of the Chloromethylation of Benzene and Toluene with Methoxyacetyl Chloride or Chloromethyl Methyl Ether and Aluminum Chloride in Nitromethane or Tin Tetrachloride in Dichloromethane. The Methoxymethyl Cation as a Remarkably Selective Common Electrophile
Franklin P. DeHaan, et al. J Org Chem. 1997 May 2;62(9):2694-2703. doi: 10.1021/jo961064o.
Vacuum line kinetics studies have been made of the reaction in nitromethane between benzene and/or toluene, methoxyacetyl chloride (MAC), and AlCl(3) to produce benzyl or xylyl chlorides, CO, and a CH(3)OH(-)AlCl(3) complex. For both arenes, the rate law appears to be R = (k(3)/[AlCl(3)](0)) [AlCl(3)](2)[MAC]. When chloromethyl methyl ether (CMME) is substituted for MAC, a similar rate law is obtained. Both chloromethylation reactions yielded similar, large k(T)()/k(B)() ratios (500-600) and similar product isomer distributions with low meta percentages ( approximately 0.4) which suggest CH(3)OCH(2)(+) or the CH(3)OCH(2)(+)Al(2)Cl(7)(-) ion pair as a common, remarkably selective, electrophile. The kinetics of MAC decomposition to CMME and CO in the presence of AlCl(3) yielded the rate law R = k(2)[AlCl(3)](0)[MAC]. Here AlCl(3) is a catalyst (no CH(3)OH is formed), and thus the rate law is equivalent to the chloromethylation rate law. All three reactions have comparable reactivities, which is consistent with rate-determining production of the electrophile. Kinetics studies of benzene or toluene with SnCl(4) and MAC or CMME in dichloromethane were also completed. With MAC and benzene the rate law is R = k(3)[SnCl(4)](0)[MAC][benzene] and with toluene R = k(2)[SnCl(4)](0)[MAC]. MAC decomposition, again followed by CO production, was unaffected by the presence of either aromatic and obeyed the rate law R = k(2)' [SnCl(4)](0)[MAC] where k(2) approximately k(2)'. Chloromethylation with CMME followed the rate law R = k(3)[SnCl(4)](0)[CMME][arene] for benzene and toluene and produced a k(T)()/k(B)() ratio and product isomer distributions very similar to those determined with AlCl(3) in nitromethane, further supporting a common electrophile. Low-temperature (13)C and (119)Sn FT-NMR and Raman spectroscopic studies suggest the existence of a weak 1:1 adduct between MAC and SnCl(4) of the type RCXO --> SnCl(4), with electron donation to the metal through carboxy oxygen. Finally, an explanation is provided for the range of chloromethylation k(T)()/k(B)() values and product isomer percentages published in the literature.
