摘要:

The synthesis of the 5′-monomethoxytrityl-2′-tert-butyldimethylsilyl-3′-levulinylribonucleosides4of the four major bases involved in the phosphite procedure for the synthesis of oligoribonucleotides is described along with the 2′,3′-isomeric derivatives6. This report describes a total protection system for nucleotide units which allows for the block condensation procedure to be used for the synthesis of long chains. The procedure is illustrated by the synthesis of a hexadecauridylic acid.

ISSN:0008-4042    

DOI:10.1139/v80-219

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

2,11-Diselena[3,3]metacyclophane and its 9,18-dimethyl derivative are prepared in ca. 7% yield from Na2Se and xylylene bromide. Wittig rearrangement and benzyne induced Stevens rearrangement gave the ring contracted [2,2]metacyclophane derivative. Attempted selenoxide elimination to produce metacyclophane-diene failed. The1Hmr spectra of the selenametacyclophane indicate that thesyn-conformer is the more stable. A general synthesis of aryl-alkenes in an 80% yield starting from benzyl phenyl selenide, alkylation with an alkyl halide, and then selenoxide elimination is given.

ISSN:0008-4042    

DOI:10.1139/v80-220

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

A fluorine-bridged silicon fluoroanion and many hexa-co-ordinate germanium and titanium fluoroanions have been identified in solution via fluorine magnetic resonance. A generalized shceme is used to correlate all fluorine chemical shift data for hexa-coordinate fluorine containing species.

ISSN:0008-4042    

DOI:10.1139/v80-221

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The potentiometric behaviour of nitrobenzene solutions of 21 trialkylammonium salts employed as membrane material has been investigated. Deviations from ideal Nernst response curves for chloride, bromide, iodide, and perchlorate sensors were explicable on the basis of partition and hydrolysis of the ion exchangers. Interference coefficients for the anion selective electrochemical sensor tridodecylammonium perchlorate could be related to the ion-exchange constant of the salt.

ISSN:0008-4042    

DOI:10.1139/v80-222

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Evidence is presented to indicate that aqueous Co2+exists as the hexaaquo-ion in equilibrium with minor amounts (upper limits 0.08% at 298 K, 7% at 625 K, at 16–25 MPa) of tetraaquocobalt(II), with ΔH ~ +17 kJ mol−1. The single visible absorption band of the supposed Co(H2O)42+has maxima at 552 nm and 486 nm in the intensity ratio 2:1. Hydrogen sulfate ion (up to 0.5 Mat least) does not complex Co2+(aq) detectably in acidic media, 290–625 K, and sulfuric acid therefore holds promise as a non-complexing strong monobasic acid for high-temperature aqueous studies. In water containing 2.0 Mor more Cl−, the tetrahedral form of cobalt(II) is CoCl42−, ΔHfor the octahedral → tetrahedral equilibrium being +62 kJ mol−1; forCoBr42−, the corresponding ΔHis +70 kJ mol−1, the greater endothermicity accounting entirely for the lower stability relative to CoCl42−.

ISSN:0008-4042    

DOI:10.1139/v80-223

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

3,17β-Dihydroxy-6-oxaestra-1,3,5(10),7-tetraen and related steroidal compounds have been synthesized in high yield via condensation of 7-methoxy-4-vinyl coumarin and 2-methyl-1,3-pentanedione. The approximate uterotrophic activity of the synthetic compounds relative to 17β-estradiol has been determined.

ISSN:0008-4042    

DOI:10.1139/v80-224

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Binuclear platinum(II) complexes of the typewhere X = H, CH3, Y = H, Br, Z = Cl, OCH3, are synthesized by the reaction of Pt2Cl4(PEt3)2with the pyrazole and sodium hydroxide in methanol. The nature of the product depends on the amount of sodium hydroxide used.

ISSN:0008-4042    

DOI:10.1139/v80-225

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The title compound belongs to space groupwith the following cell parameters:a = 6.304,b = 11.925,c = 25.946 Å, α = 85.76, β = 89.78, γ = 83.57°, andZ = 4. The structure was solved by the heavy-atom method and refined on 2570 nonzero reflections to anRfactor of 0.044. In the two crystallographically independent [Adeninato(CH3Hg)3]2+ions, methylmercury groups are linearly bonded to N(3), N(7), and N(9) of a deprotonated adenine ring, forming Hg—N bonds of normal lengths (ave. 2.08 Å) for two-coordinated mercury. One half of the complex cations are associated in a dimeric unit by a pair of stronghydrogen bonds, while the others are packed as individual species in the crystal. The structure is stabilized by a number of contacts between mercury and perchlorate oxygens.

ISSN:0008-4042    

DOI:10.1139/v80-226

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

(±)-Deoxybutaclamol, C25H31N, crystallizes in space groupP21/awith cell dimensions:a = 16.626(3),b = 10.646(2),c = 11.278(3) Å, β = 90.47(4)°. The structure was solved by direct methods using the QTAN program. The coordinates were refined by block-diagonal least-squares calculations toR = 0.052 for 3147 observed reflections.The structure of (±)-deoxybutaclamol was found to be very similar to that of equipotent (±)-butaclamol and is in agreement with that assigned on the basis of chemical, spectral, crystallographic, and pharmacological studies. This confirmation validates the coordinates of a lipophilic accessory binding site in a proposed model of the central dopamine receptor.

ISSN:0008-4042    

DOI:10.1139/v80-227

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

L-3-Methoxy-4-hydroxyphenylalanine was fluorinated directly with XeF2in CH2Cl2at −60 °Cinvacuo. After hydrolysis with 48% aqueous HBr,L-6-fluorodopa was obtained. The yield, based on XeF2, was 25%. This reaction might be applied when chiral biomolecules are to be tagged with fluorine-18.

ISSN:0008-4042    

DOI:10.1139/v80-228

出版商:NRC Research Press    

年代:1980

数据来源: NRC