Efficient synthesis and facile polymerization of some cyclic bisphenol o-phthalates

A series of new macrocyclic aromatic esters have been efficiently synthesized from o-phthaloyl dichloride and various bisphenols, and unambiguously characterized by a combination of GPC, MS(FAB), FTIR and NMR. These macrocyclic oligomers undergo facile ring-opening polymerization in the presence of anionic initiators to give high molecular weight polyarylates.

Efficient cleavage of ribonucleoside 3',5'-cyclic phosphates and deoxyribonucleoside 3',5'-cyclic phosphate by lanthanides

The cleavage of 3',5'-cAMP, 3',5'-cGMP and 3',5'-dcAMP by lanthanides has been investigated by HPLC and H-1 NMR. Rapid cleavage of cAMP, cGMP and dcAMP by Ce(III) under air at pH 8 and 37 degrees C has been observed. Regioselective cleavage of P-O(5') bond in cAMP, cGMP and dc;aMP tu give the corresponding 3'-AMP, 3'-GMP and 3'-dAMP by lanthanide chlorides has been achieved, and 3'-AMP and 3'-GMP are cleaved to adenosine(A) and guanosine(CT) more slowly, respectively, The notable difference in reactivity between Ce(III) and the other lanthanide ions under air has also been studied. The cleavage is enhanced with the increase in the molar fraction of Ce(IV). The fast cleavage of cAMP by Ce(III) under air at pH 8 is ascribed to the resultant Ce(IV) in the reaction mixture.

One-step chromatography method for efficient separation and purification of R-phycoerythrin from Polysiphonia urceolata

Phycoerythrins have been widely used in food, cosmetics., immunodiagnostics and analytical reagents. An efficient one-step chromatography method for purification of R-phycoerythrins from Polysiphonia urceolata was described in this paper. Pure R-phycoerythrin was obtained with an absorbance ratio A(565)/A(280) of 5.6 and a high recovery yield of 67-33%, using a DEAE-Sepharose Fast Flow chromatography with a gradient elution of pH, alternative to common gradient elution of ionic strength. The absorption spectrum of R-phycoerythrin was characterized with three absorbance maxima at 565, 539 and 498 mum, respectively and the fluorescence emission spectrum at room temperature was measured to be 580nm. The results of native-PAGE. and SDS-PAGE showed no contamination by other proteins in the phycoerythrin solution. which suggests an efficient method for the separation and purification of R-phycoerythrins from Polysiphonia urceolata. (C) 2004 Elsevier B.V. All rights reserved.

An efficient method for DNA isolation from red algae

A simple, inexpensive and efficient method was developed for rapid isolation of total genomic DNA from 15 red algal species. It resulted in 0.1 mug high quality DNA from 1 mg fresh algal material, with an A(260)/A(280) ratio of 1.68 - 1.90. Using this rapidly isolated DNA, the 18S ribosomal RNA genes ( rDNA) and the nuclear ribosomal DNA of the internal transcribed spacer (ITS) regions were amplified. The tested DNA was suitable for restriction endonuclease digestion, genetic marker analysis and polymerase chain reaction (PCR) amplification, and may be valid for other genetic manipulation.

An efficient combination of supercritical fluid extraction and high-speed counter-current chromatography to extract and purify homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler

Supercritical fluid extraction (SFE) was used to extract homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler. The optimization of parameters was carried out using an orthogonal test L-9 (3)(4) including pressure, temperature, dynamic extraction time and the amount of modifier. The process was then scaled up by 100 times with a preparative SFE system under the optimized conditions of 25 MPa, 55 degrees C, 4.0 h and 25% methanol as a modifier. Then crude extracts were separated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/ACN/water (1.8:1.0:1.0:1.2:1.0 v/v). There three homoisoflavonoidal compounds including methylophiopogonanone A 6-aldehydo-isoophiopogonone A, and 6-formyl-isoophiopogonanone A, were successfully isolated and purified in one step. The collected fractions were analyzed by HPLC. In each operation, 140 mg crude extracts was separated and yielded 15.3 mg of methylophiopogonanone A (96.9% purity), 4.1 mg of 6-aldehydo-isoophiopogonone A (98.3% purity) and 13.5 mg of 6-formyl-isoophiopogonanone A (97.3% purity) respectively. The chemical structure of the three homoisoflavonoids are identified by means of ESI-MS and NMR analysis.

An efficient methodology for cryopreservation of spermatozoa of red seabream, Pagrus major, with 2-mL cryovials

The aim of this study was to optimize the cryopreservation protocols for the sperm of red seabream, Pagrus major. The 2-mL cryovials and programmable freezer were employed for cryopreservation. Six extenders, six cryoprotectants in various concentrations ranging from 6 to 20% (v/v), four cooling rates, and three thawing temperatures were evaluated by postthaw sperm motility and fertility. The ratio of sperm to egg for postthaw sperm fertilization trials was experimentally standardized and was optimal at 500:1. The best motility of postthaw sperm (79.4 +/- 4.7% to 88.6 +/- 8.0%), fertilization rates (89.6 +/- 2.9 to 95.6 +/- 1.9%), and hatching rates (85.3 +/- 5.1% to 91.4 +/- 4.3%) were achieved when Cortland extender, dimethyl sulfoxide (15, 18, and 20%) or ethylene glycol (9, 12%) as cryoprotectants, 20 C/min as the cooling rate, and 40 C as the thawing temperature were employed. Moreover, the results on embryonic development were not significantly different between cryopreserved sperm and fresh sperm during incubation process. In conclusion, these methods of cryopreservation of red seabream sperm are suitable for routine aquaculture application and preservation of genetic resources.

Trichloroacetimidate as an efficient protective group for alcohols

The trichloroacetimidate is disclosed to be a general and efficient protective group for alcohols, which can be deprotected under mild acidic, basic, or neutral conditions, and has orthogonal stability with the acetate and tert-butyldimethylsilyl (TBS) protections.

An efficient synthesis of dicyclohexylmethyl diazoacetate

Dicyclohexylmethyl diazoacetate was synthesized in excellent yield from the corresponding glycinate. which was derived in high yield from dicyclohexylmethyl chloroacetate via azide substitutuion, and reduction.

An efficient approach to modify the catalyst activity for the hydrogenation of nitrobenzene

The addition of a suitable amount of PPh3 to PdCl2 or PdCl2(PhCN)(2) in situ can considerably increase the catalytic activity in the hydrogenation of nitrobenzene, while the catalytic activities of PdCl2 (reduced)+PPh3, PdCl2(PPh3)(2) and Pd(PPh3)(4) are very poor. The poisoning of catalyst by mercury indicates that the catalytically active species are composed of Pd(0) colloidal particles. Transmission electron micrographs show that the size of nanometric Pd(0) particles of PdCl2 with PPh3 added in situ is smaller than that of PhCl2(PPh3) or PdCl2 (reduced)+PPh3. A synergic effect of bimetallic catalysts such as PdCl2+nPPh(3)+NiCl2 (n= 0.5, 1) and PdCl2(PhCN)(2)+PPh3+FeCl3 gives rise to a further increase in the catalytic activity.

Mild and efficient copper-catalyzed N-arylation of alkylamines and N-H heterocycles using an oxime-phosphine oxide ligand

A mild and efficient copper-catalyzed system for N-arylation of alkylamines and N-H heterocycles with aryl iodides using a novel, readily prepared and highly stable oxime-functionalized phosphine oxide ligand was developed. The coupling reactions could even be performed in solvent-free conditions with moderate to good yields. (c) 2005 Elsevier Ltd. All rights reserved.

Highly efficient copper-catalyzed N-arylation of alkylamines with aryl iodides using phosphoramidite as ligand

A mild and highly efficient copper-catalyzed system for N-arylation of alkylamines with aryl iodides using binaphthol-based phosphoramidites as ligands was developed. The phosphoramidite ligands are stable, cost-effective and easily prepared from inexpensive, commercially available starting materials using a simple, efficient method. (c) 2005 Elsevier B.V. All rights reserved.