关于空间群判断失误的札记Ⅱ.P空间群的修正

列举１６ 例按Ｐ１ 解出的晶体结构,其空间群应描述为单斜晶系的Ｃ２／ｃ,并讨论从Ｐ１ 修正为三方的Ｒ３ 和四方的Ｉ４１／ａ 的晶体结构各１ 例。分析揭示判断失误的线索。最后强调在结构报告中完整发表原子坐标数据的重要意义。     

The synthesis of phosphonic acid and phosphate analogues of glycerol-3-phosphate and related metabolites

A convenient route is described for the preparation of the isosteric phosphonic acid analogue of glycerol-3-phosphate, 3,4-dihydroxybutyl-1-phosphonic acid, in both enantiomeric forms and the racemic modification, starting with readily available materials. The (S)-enantiomer, that of absolute configuration corresponding to that of sn-glycerol-3-phosphate, has been found to be a growth inhibitor of several bacteria at low concentration. The synthetic route described is of particular value as it facilitates the preparation of a series of phosphonic adds and phosphates of related structure, in their enantiomeric forms, which are also of interest for metabolic regulation. These include the 3,4-epoxybutyl-1-phosphonate and a phosphate analogue of glycerol-3-phosphate with the related homodiglyceride. Investigations are continuing in the evaluation of the biological activity of the materials synthesized. A method is also described for the synthesis of the carbon-14 labelled 3-carboxy-3-hydroxybutyl-1-phosphonic acid, an analogue of phosphoglyceric acid known to serve as a substitute for the natural material in several biochemical processes.     

4-substituted-1,2,3,4-tetrahydro-3,3-dimethylisoquinolines. II.

A practical synthesis (Scheme I) is described for the preparation of a series of 4-substituted-3,3-dimethyl-1,2,3,4-tetrahydroisoquinolines ( 3 ). Treatment of α-(1-amino-1-methylethyl)arylmethanols or α-(1-amino-1-methylethyl)heteroarylmethanols ( 5 ) with aromatic aldehydes gave imines 7 from which amino alcohols 8 were derived by reduction with potassium borohydride. Acid catalyzed cyclization of 8 yielded 3 . An acyl substituent was installed by Friedel-Crafts acylation as a final step. The biological activities of 3a (1) are briefly described.     

2,3,5,6-Tetrafluorbenzoldisulfonsäure aus pentafluorbenzolsulfonsäure

The sulfonation of pentafluorobenzene with liquid SO₃ to pentafluorbenzenesulfonic acid at normal pressure as well as its conversion to 1-thiol-2,3,5,6-tetrafluorobenzenesulfonic acid, 2,3,5,6-tetrafluorobenzenedisulfonic acid monochloride and 2,3,5,6-tetrafluorobenzenedisulfonic acid are described. The preparation of anhydrous pentafluorobenzenesulfonic acid and 2,3,5,6-tetrafluorobenzenedisulfonic acid is described.     

Spectrophotometric determination of iron and cobalt with Ferrozine and dithizone

Procedures are described whereby iron (1–50 μg) and cobalt (1–25 μg) are determined spectrophotometrically, iron as iron(II) with the disodium salt of 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (Ferrozine) and cobalt as the cobalt(III) dithizonate complex. The reduction to iron(II) prevents interference of iron(III) in the cobalt determination, and both metals can be determined in the same portion of sample solution. Removal of interference by other metal ions is described.     

Chemical behaviours of 3-[1''''-chloro-3''''-(2"-phenyl-1",3"-oxazol-5"-one-4"-ylidene)propen-l''''-yl]coumarin towards some nucleophilic reagents

The chemical behaviours of 3-[1'-chloro-3'-(2"-phenyl-1",3"-oxazol-5"-one-4"-ylidene)-propen-1'-yl]coumarin towards nucleophilic reagents (such as hydrolysis,aminolysis,hydroxyl-aminolysis,methanolysis and hydrazinolysis) were described.     

Reaction of ethyl 3-ethoxymethylene-2,4-dioxovalerate with monosubstituted hydrazines

Reactions of ethyl 3-ethoxymethylene-2,4-dioxovalerate (1) with phenyl- and methylhydrazines are described. While the reaction of 1 with phenylhydrazine gave a mixture of ethyl 4-acetyl-1-phenylpyrazole-5-carboxylate (4) and ethyl 5-methyl-1-phenylpyrazole-4-glyoxylate (5), 1 reacted with methylhydrazine to give ethyl 4-acetyl-1-methylpyrazole-3-carboxylate (14) as the sole product.     

Synthesis of 2′,3′-dihydrospiro[benzofuran-2(3H),4′(1′-H)isoquinoline]s. A novel heterocyclic ring system

The synthesis of a novel 2′,3′-dihydrospiro(benzofuran-2(3H),4′(1′H)isoquinoline] ring system ( IV ) by a nucleophilic aromatic fluoride displacement-cyclization is described. Preparation of various derivatives of IV as well as the precursor 4-(2-fluorobenzyl)-1,2,3,4-tetrahydro-4-isoquinolinols is also described.     

Synthesis of 2-substituted isothiazolopyridin-3-ones

The synthesis of some 2-substituted derivatives 1–4 of all four isomeric isothiazolopyridin-3-ones is described. Several novel 1,2-dithiolopyridin-3-ones and 3-thiones were prepared as intermediates.     

Ein neuer Süßstoff aus der Indolreihe

The synthesis of 3, 4-dehydro-2-(3-indolylmethyl)-1-methyl-piperidine-4-carboxylic acid, a new dulcifiant of the indole series being twice as sweet as saccharine, is described.     

Chemical behaviours of 3-[1′-chloro-3′-(2″-phenyl-1″,3″-oxazol-5″-one=4″-ylidene)propen-1′-yl]coumarin towards some nucleophilic reagents

The chemical behaviours of 3-[1′-chloro-3′-(2″-phenyl-1″,3″-oxasol-5″-one-4″-ylidene)-propen-1′-yl]coumarin towards nucleophilic reagents (such as hydrolysis, aminolysis, hydroxyl-aminolysis, methanolysis and hydrazinolysis) were described.     

Synthesis, structural determination and photo-antiproliferative activity of new 3-pyrazolyl or -isoxazolyl substituted 4-hydroxy-2(1H)-quinolinones

A convenient route to new 3-quinolinonyl-pyrazoles and isoxazoles is described through cyclization of 3-[(E)-3-(dimethylamino)-2-propenoyl]-4-hydroxy-1-methyl-2(1H)-quinolinone. The phototoxicity as well as the cytotoxic activities of the title compounds are evaluated against leukemia- and adenocarcinoma-derived cell lines in comparison to the normal human keratinocytes.     

Crystal structure,dissociation and zwitterion formation in 2,6-diaryl-1(3)-oxo-3(1)-hydroxy-5(7)-imino-7(5)-amino-1 H,5H-(3-H,7H)-pyrazolo[1,2-a]pyrazoles

Single crystal X-ray analysis and quaternization of 2,6-diphenyl-1(3)-oxo-3(1)-hydroxy-5(7)-imino-7(5)-1H,-5H[3H,7H)-pyrazolo[1,2-a]pyrazole is described. The dissociation constants are determined and compared with those of 4-phenyl-1,2-dimethyl-3(5)-oxo-5(3)-hydroxypyrazole and 4-phenyl-3,5-diaminopyrazole. The quaternization of the latter compound is also described. The influence of electron donating substituents at the cationic moiety on the electronic spectra of such paraionic systems is discussed. The title products exist in the solid state as zwitterions and probably as covalent species in solution.     

Reactions of 1,2-dialkyl-3-pyrazolidinones

The condensation of 1,2-dialkyl-3-pyrazoIidinones (1) with a series of aldehydes, ketones and esters in the presence of sodium hydride is described. Alkylation of I with several alkyl bromides gave 4-alkyl substitution products in modest yield and reaction of 1,2,4-trimethyl-3-pyrazolidinone with n-butyl bromide gave a 4,4-dialkylation product. Compound 1 reacted with aryl Grignard reagents to form 3-aryl-3-pyrazoIines whereas the corresponding products were not realized in the case of alkyl Grignards. The reduction of a single example of 1 as well as the reduction of two 3-pyrazolines to pyrazolidines is also reported.     

Synthesis of racemic, 2-(alkylthio)-6-(1-hydroxyethyl) penems; attempted penem synthesis via copper (I) - promoted cyclisations

Stereocontrolled syntheses of the diastereoisomeric 6-(1-hydroxyethyl)-2-ethylthio and 2-(2-aminoethylthio)-penem-3-carboxylates from a common monocyclic azetidinone precursor are described. Cu (I)-promoted cyclisation of suitable N/C-3 secopenems is shown to yield “isopenems” (7-oxo-2-thia-1-azabicyc1o[3.2.0]-hept-3-enes) as the sole bicyclic product.     

Synthesis of key intermediates to 20(R)-and 20(S)-trifluoromethyl-23,24-dinor-25-hydroxy-cholesterol and VD3 analogs

Synthesis of 20(R)-and 20(S)-trifluoromethyl substituted steroids as the key intermediates (1a, 1b) to 23,24-dinor-20-trifluoromethyl-25-hydroxy-cholesterol and VD3 analogs, using trifluoromethyltrimethylsilane (CF₃SiMe₃) as a trifluoromethylating agent, was described.     

L-proline/urea catalyzed,novel, and eco-friendly synthesis of coumarin substituted-3-indoloxanthenes

A green and eco-friendly synthesis of coumarin substituted-3-indoloxanthenes 4(a-l) has been developed using urea/L-proline as simple catalyst. Two efficient methods have been described for the synthesis of these 3-indoloxanthene derivatives. In the first method, Knoevenagel condensation, then Pinner cyclisation followed by 1,4 addition between 4-hydroxy-1-methyl-2-oxo-1,2-dihydrocoumarin-3-carbaldehyde 1(a-b) , with cyclohexane-1,3-dione (2) and indole 3(a-f) using of L-proline as catalyst was described. In the second method, urea/thiourea catalyzes the same reaction at 100°C for 10 minutes to afford the title compounds 4(a-l) . These two protocols involve eco-friendly and inexpensive catalysts, give excellent yields of the clean products without the need of column chromatography for their isolation or purification.     

Alkaloids from Hippeastrum morelianum Lem. (Amaryllidaceae)

The Amaryllidaceae family has proven to be a rich source of active molecules. As part of an ongoing project, we report a phytochemical study of Hippeastrum morelianum (Amaryllidaceae), from which we have isolated two homolycorine-type alkaloids, the new 2α,7-dimethoxyhomolycorine (1) and the poorly described candimine (2), as well as six known alkaloids: tazettine, pretazettine, 3-epimacronine, haemanthamine, hamayne and trisphaeridine. For reference purposes, the NMR of the isolated compounds was unequivocally described, based on 2D NMR measurements including (1)H-(1)H COSY, (1)H-(1)H NOESY, HSQC and HMBC.     

Studies towards the enantioselective synthesis of 5,6,8-trisubstituted amphibian indolizidine alkaloids via enaminone intermediates

Investigations aimed at the enantioselective total synthesis of indolizidine 223A, a recently described 5,6,8-trisubstituted indolizidine alkaloid from a dendrobatid frog, are described. tert-Butyl (2R,3R)-3-amino-2-ethylhexanoate and its (2S,3R)-diastereomer, prepared in several steps from lithium N-benzyl-N-[(1R)-1-phenylethyl]amide and tert-butyl (2E)-hex-2-enoate by the Davies protocol, served as chiral building blocks from which two complementary suites of diastereomeric intermediates were made en route to pivotal tert-butyl 3-[2-(alkoxycarbonylmethylene)pyrrolidin-1-yl]-2-ethylhexanoate intermediates 20 and 21. Cyclisation of these enaminones, achieved by acid hydrolysis of the tert-butyl esters and activation of the liberated carboxylic acids as mixed anhydrides, afforded 6-ethyl-7-oxo-5-propyl-1,2,3,5,6,7-hexahydroindolizine-8-carboxylate esters 28 and 29. Several further transformations of these potential scaffolds for the synthesis of the target alkaloidal systems are also reported.     

Synthesis and reduction reactions of pyridones and 5-acyl-2-methoxypyridines

The synthesis of a series of pyridones, from their 2-hydroxypyridine or 2-methoxypyridine precursors, is described, along with studies into their reductions to saturated heterocycles. A number of 5-acylpyridones were prepared and were evaluated as substrates for asymmetric transfer hydrogenation prior to conversion to saturated heterocycles. The enantioselective reduction of 5-acetyl-1-benzylpyrimidine-2,4(1H,3H)-dione is also described.