A New, Convenient Reductive Procedure For The Deprotection Of 4-Methoxybenzyl (Mpm) Ethers To Alcohols

Selective introduction and removal of protecting groups is of great significance in organic synthesis.l The benzyl ether function is one of the most common protecting groups for alcohols. Selective oxidative removal of the 4-methoxybenzyl (MPM) ethers in the presence of benzyl ethers made the MPM moiety an alternative protecting group, and its utility in carbohydrate chemistry is well established. Several procedures have been developed for the cleavage of the 4-methoxybenzyl moiety, e.g. DDQ oxidation (eq 1),2e lectrochemical ~xidationh,~om ogeneous electron t r a n~f e rp,~ho toinduced single electron t r an~f e rb,o~ro n trichloride-dimethyl sulfide,6e tc. However, in all these methods isolation of the alcohol from the inevitable byproduct, 4-methoxybenzaldehyde [also dichlorodicyanohydroquinone (DDHQ) in the most commonly used method employing DDQI can be troublesome. Recently Wallace and Hedgetts7 discovered that acetic acid at 90 "C cleaves the aromatic MPM ethers into the corresponding phenols and 4-methoxybenzyl acetate (eq 21, whereas the aliphatic MPM ethers generated, instead of alcohols, the corresponding acetates (eq 3). Complimentary to this methodology, herein we report that sodium cyanoborohydride and boron trifluoride etherate reductively cleaves, cleanly and efficiently, the aliphatic MPM ethers to an easily separable mixture of the corresponding alcohols and 4-methylanisole

Preparation of lamellar and hexagonal forms of mesoporous silica and zirconiaby the neutral amine route: lamellar-hexagonal transformation in the solid state

The chain length of the surfactant and the solvent composition are two of the factors that determine whether the lamellar or the hexagonal form of mesoporous SiO2 (or ZrO2) is formed by the neutral amine route; a lamellar-hexagonal transformation occurs on removal of the amine from the former.

Hydrogen and fluorine in crystal engineering: systematics from crystallographic studies of hydrogen bonded tartrate-amine complexes and fluoro-substituted coumarins, styrylcoumarins and butadienes

Three aspects of crystal engineering in molecular crystals are presented to emphasize the role of intermolecular interactions and factors influencing crystal packing. Hydrogen bonded tartrate-amine complexes have been analyzed with the propensity for formation of multidirectional hydrogen bonding as a key design element in the generation of materials for second harmonic generation (SHG). The invariance of the framework in DBT and its possible implications on SHG is outlined. The role of Fluorine in orienting molecules of coumarins, styrylcoumarins and butadienes for photodimerization is described with particular emphasis on its steering capability. Usage of coumarin as an design element for the generation of polymorphs of substituted styrylcoumarins is examined with specific examples.

Prop-2-ynyl as a protective group for carboxylic acids: A mild method for the highly selective deprotection of prop-2-ynyl esters using tetrathiomolybdate

It is shown that prop-2-ynyl esters are useful protecting groups for carboxylic acids and that they are selectively deprotected in the presence of other esters on treatment with tetrathiomolybdate under mild conditions.

Microbial transformation of a fungicide-derived amine, dimethyl-p-phenylene diamine by Alcaligenes DM4

Abstract Microbial transformation of N, N-dimethyl-p-phenylene diamine (DMPDA), a microbial product formed from the fungicide fenaminosulf (p-dimethylaminobenzenediazo sodium sulfonate) was studied by enriching microbes in soils treated with the amine. Microorganisms isolated from DMPDA-treated soil belonged to the genera of Micrococcus, Alcaligenes, and Corynebacterium. Of the various isolates, Alcaligenes DM4 showed maximal growth on DMPDA utilizing it as sources of carbon and nitrogen. When grown in mineral salts basal medium containing 0.05% DMPDA to serve as carbon and nitrogen sources, Alcaligenes DM4 grew exponentially up to 18 h. Even though the characterization of the complete pathway of microbial degradation of DMPDA could not be carried out due to the auto-oxidation of the compound, the initial transformation product of DMPDA by Alcaligenes DM4 has been identified as a dimer. The dimer is generated into the culture medium presumably by the extra-cellular oxidase of Alcaligenes DM4. It is suggested that the risk-benefit evaluation on the use of fenaminosulf is to be made taking into consideration the microbial transformations of the fungicide.

Partial purification and properties of a transamidinase from Lathyrus sativus seedlings. Involvement in homoarginine metabolism and amine interconversions

A transamidinase was purified 463-fold from Lathyrus sativus seedlings by affinity chromatography on homoarginine--Sepharose. The enzyme exhibited a wide substrate specificity, and catalysed the reversible transfer of the amidino groups from donors such as arginine, homoarginine and canavanine to acceptors such as lysine, putrescine, agmatine, cadaverine and hydroxylamine. The enzyme could not be detected in the seeds, and attained the highest specific activity in the embryo axis on day 10 after seed germination. Its thiol nature was established by strong inhibition by several thiol blockers and thiol compounds in the presence of ferricyanide. In the absence of an exogenous acceptor, it exhibited weak hydrolytic activity towards arginine. It had apparent mol.wt. 210000, and exhibited Michaelis--Menten kinetics with Km 3.0 mM for arginine. Ornithine competitively inhibited the enzyme, with Ki 1.0 mM in the arginine--hydroxylamine amidino-transfer reaction. Conversion experiments with labelled compounds suggest that the enzyme is involved in homoarginine catabolism during the development of plant embryo to give rise to important amino acids and amine metabolites. Presumptive evidence is also provided for its involvement in the biosynthesis of the guanidino amino acid during seed development. The natural occurrence of arcain in L. sativus and mediation of its synthesis in vitro from agmatine by the transamidinase are demonstrated.

X-Ray Structure Of A Ternary Metal-Complex - Copper(Ii) Inosine 5'-Monophosphate Imidazole - Metal-Binding To The N(7) Atom Of The Nucleotide In A Mixed-Ligand System Containing An Aromatic Amine

A ternary metal-nucleotide complex, Na2[Cu(5’-IMP)2(im)o,8(H20)l,2(H20)2h]as~ 1be2e.n4 pHr2ep0a,r ed and its structure analyzed by X-ray diffraction (5’-IMP = inosine 5’-monophos hate; im = imidazole). The complex crystallizes in space group C222, with a = 8.733 (4) A, b = 23.213 (5) A, c = 21.489 (6) 1, and Z = 4. The structure was solved by the heavy-atom method and refined by full-matrix least-squares technique on the basis of 2008 observed reflections to a final R value of 0.087. Symmetry-related 5’-IMP anions coordinate in cis geometry through the N(7) atoms of the bases. The other cis positions of the coordination plane are statistically occupied by nitrogen atoms of disordered im groups and water oxygens with occupancies 0.4 and 0.6, respectively. Water oxygens in axial positions complete the octahedral coordination of Cu(I1). The complex is isostructural with C~S-[P~(S’-IMP),(NH~)~a] m”,o del proposed for Pt(I1) binding to DNA. The base binding observed in the present case is different from the typical ”phosphate only” binding shown from earlier studies on metal-nucleotide complexes containing various other ?r-aromatic amines.

Theoretical studies of lithium bonding in lithium chloride/aliphatic amine complexes

In the systematic study of amine … LiCl [amines = NH3, CH3NH2, (CH3)2NH] complexes the possibility of an ion-pair structure and the effect of methylation on the stabilization energy is investigated. ΔEis evaluated by the SCF/4-31G method and augmented by the approximate dispersion energy calculated perturbationally. The interaction energy decreases with the increasing number of methyl groups in the amine. The dispersion energy plays a negligible role in the stabilization of complexes. None of the systems studied are ion pairs; their Li bonds are of a so-called molecular type. Due to the divergence of the multipole expansion, the attempt to correct the 4-31G stabilization energies via the electrostatic energy fails. The relative order of the ΔE in the series of complexes is verified instead in the extended basis set calculation. The lithium bonds are compared with their H-bonded analogues.

Thermal decomposition of ethyl and isopropyl amine perchlorates

Thermal decomposition of ethyl and isopropyl amine perchlorates has been studied by methods such as DTA, TG, isothermal weight loss measurements and the decomposition products have been analyzed in a mass spectrometer. Activation energy values for thermal decomposition have been calculated fromagr-t plots. The proton transfer dissociation mechanism proposed for the thermal decomposition of ammonium perchlorate (AP) has been extended to explain the decomposition products of these twosubstituted amine perchlorates.

Amine biosynthesis in Lathyrus sativus seedlings

The biosynthesis of certain amines in Lathyrus sativus seedlings was studied in isolated shoots and cotyledons. In shoots, arginine was about 14 times more efficient than ornithine for the synthesis of agmatine, putrescine, spermidine and spermine. Isotope dilution experiments, and the changes in specific activities of the 4 amines with time when 14C-arginine served as the precursor, indicated that putrescine and the polyamines were formed mainly from arginine, via agmatine. Similar experiments showed that cadaverine was formed at least in part from homoarginine, though lysine was ca 4 times more effective as a precursor. The pattern of changes in specific activity of homoagmatine and cadaverine with time when 14C-homoarginine served as the precursor support the conclusion that homoarginine and arginine follow analogous metabolic routes in the biosynthesis of putrescine and cadaverine respectively.

Amine levels in Lathyrus sativus seedlings during development

In growing Lathyrus sativus seedlings, the levels of DNA, RNA and protein markedly decreased in the cotyledons and progressively increased in the embryo-axis. In cotyledons, spermidine and spermine contents were substantially reduced while those of agmatine and putrescine were sharply increased. By contrast the embryo-axis progressively accumulated relatively larger amounts of agmatine, homoagmatine. putrescine, cadaverine, spermidine and spermine in parallel with similar changes in its DNA, RNA and protein content. While the cotyledons contained ca 50% of the total agmatine and putrescine present in the plant embryo by day 10, the embryo-axis, though representing less than 20% of the dry wt, contained 90 and 75% of total cadaverine and homoagmatine respectively of the seedlings. Spermidine and spermine levels of this tissue were also comparatively higher, being of the order of 80 and 50% respectively of the total. The root and shoot portions of the embryo-axis also exhibited a similar relationship between changes in DNA, RNA and protein and all the above amines during development. However, the polyamine content of the shoots was relatively higher than those of the roots during the growth period.

Synthesis and Structure-Activity Correlation Studies of Secondary- and Tertiary-Amine-Based Glutathione Peroxidase Mimics

In this study, a series of seeondary- and tertiary-amino-substituted diaryl diselenides were synthesized and studied for their glutathione peroxidase (GPx) like antioxidant activities with H2O2, cumene hydroperoxide, or tBuOOH as substrates and with PhSH or glutathione (GSH) as thiol cosubstrates. This study reveals that replacement of the tert-amino groups in benzylamine-based diselenides by sec-amino moieties drastically enhances the catalytic activities in both the aromatic thiol (PhSH) and GSH assay systems. Particularly, the N-propyl- and N-isopropylamino-substituted diselenides are 8-18 times more active than the corresponding N,N-dipropyl- and N,N-diisopropylamine-based compounds in all three peroxide systems when GSH is used as the thiol cosubstrate. Although the catalytic mechanism of sec-amino-substituted disclenides is similar to that of the tert-amine-based compounds, differences in the stability and reactivity of some of the key intermediates account for the differences in the GPx-like activities. it is observed that the sec-amino groups are better than the tert-amino moieties for generating the catalytically active selenols. This is due to the absence of any significant thiol-exchange reactions in the selenenyl sulfides derived from sec-amine-based diselenides. Furthermore, the seleninic acids (RSeO2H) derived from the sec-amine-based compounds are more stable toward further reactions with peroxides than their tert-amine-based analogues.

Amine-Templated Aluminoborates Exhibiting Graphite and Diamond Nets

A solvothermal reaction of Al2O3, H3BO3, pyridine, and H2O at 180 degrees C/7 days in the presence of organic amine molecules gave rise to four new aluminoborates, [(C6H18N2)(AlB6O13H3)], I; [(C5H16N2) (AlB5O10)]center dot 2H(2)O, II; [(C5H16N2)-(AlB5O10)], III; and [(C5H17N3)(AlB5O10)] center dot H2O, IV, with two- and three-dimensional structures. All the structures have been formed by the connectivity involving Al3+ ions and [B5O10] cyclic pentaborate units. In 1, the 3-connected trigonal nodes form a layer that resembles a graphite structure has been observed. The compounds II, III, and IV, have 4-connected nodes that forms a diamond related three-dimensional structure. The formation of solvatomorphs in II and III is noteworthy and has been observed first time in a family of amine template aluminoborates. A comparison of the various aluminoborate structures reveals subtle relationships between the organic amines (length of the amines) and the final framework structures. The compounds have been characterized using a variety of techniques including IR, second-order optical behavior, and MAS NMR studies.

Highly biocompatible and water-dispersible, amine functionalized magnetite nanoparticles, prepared by a low temperature, air-assisted polyol process: a new platform for bio-separation and diagnostics

A low temperature polyol process, based on glycolaldehyde mediated partial reduction of FeCl3 center dot 6H(2)O at 120 degrees C in the presence of sodium acetate as an alkali source and 2,2'-(ethylenedioxy)-bis-(ethylamine) as an electrostatic stabilizer has been used for the gram-scale preparation of biocompatible, water-dispersible, amine functionalized magnetite nanoparticles (MNPs) with an average diameter of 6 +/- 0.75 nm. With a reasonably high magnetization (37.8 e.m.u.) and amine groups on the outer surface of the nanoparticles, we demonstrated the magnetic separation and concentration implications of these ultrasmall particles in immunoassay. MRI studies indicated that these nanoparticles had the desired relaxivity for T-2 contrast enhancement in vivo. In vitro biocompatibility, cell uptake and MR imaging studies established that these nanoparticles were safe in clinical dosages and by virtue of their ultrasmall sizes and positively charged surfaces could be easily internalized by cancer cells. All these positive attributes make these functional nanoparticles a promising platform for further in vitro and in vivo evaluations.

Spectroscopic studies of the donor properties of triphenyl-amine, -phosphine, -arsine and -stibine interaction with iodine and phenol

The interaction of iodine with triphenylamine ,tripheny lphosphine, triphenylarsine and triphenystibine has been investigated by electronic spectroscopy. Transformation of the outer charge-transfer complexes to the inner complexes (quarternary salts) has been examined. The relations of the ionization potentials of the donors with the hvc.t have been discussed and various c.t. parameters have been estimated. Hydrogen bonding of these donors with phenol have been reported.