ISSN:0021-2148    

DOI:10.1002/ijch.197200074

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.197200075

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractA study of the dipole moments of xanthone, thioxanthone and their halogeno‐derivatives leads to the conclusion that these molecules are not planar. In the xanthene and thioxanthene series, the dipole moments as well as the NMR spectra can be explained by a planar or a non‐planar but rapidly inverting model. In the acridan series, the NMR spectra of N‐acylacridans show that the molecule is non‐planar and inverts. The barrier is 11.7, 13.1 and 13.1 Kcal/mole for the N‐acetyl‐, N‐chloroacetyl‐ and N‐iodoacetyl derivatives, respectively. Equally, it has been observed that at low temperature the rotation around the XCH2CO bond in the halogenoacetylacr

ISSN:0021-2148    

DOI:10.1002/ijch.197200076

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe reversible photocyclisation ofcis‐stilbene analogues to the corresponding dihydrophenanthrenes is not slowed down at high viscosities of the medium. Its attenuation at low temperatures is a true temperature effect. Methylation affects the photocylisation significantly only if it results in strong steric interactions in the cyclisation product. Photocyclodehydrogenation of stilbenes with oxygen to the corresponding phenanthrene analogues passes through the 4a, 4b‐dihydrophenanthrenes, and can be sensitized by various compounds at low concentrations. Photo‐oxidation with iodine probably involves dehydrogenation of ground‐state dihydrophenanthrene with atomic iodine. Electronically excited dihydrophenanthrenes may also be involved in the photo‐

ISSN:0021-2148    

DOI:10.1002/ijch.197200077

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractSeveral aspects of the binding of peptidyl‐tRNA toE. coliribosomes were studied. TheE. colibinding factor (EF1) does not increase the rate of peptidyl‐tRNA binding. From the results obtained it was concluded that two molecules of Gly2Phe‐tRNA can bind to one and the same ribosome, but no new peptide bond was formed. Gly, Phe‐tRNA at the A site inhibited the puromycin reaction of Gly2Phe‐tRNA at the P site of the same ribosome. The binding of peptidyl‐tRNA at the P site activates the adjacent A site for aminoacyl

ISSN:0021-2148    

DOI:10.1002/ijch.197200078

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe thermal reactions of 1‐aryl‐1‐cyclopropylethylenes and 1,1‐dicyclopropylethylene with pentacarbonyliron are investigated. Reactions of the former substrates yield 2‐aryl‐1,3‐pentadiene‐tricarbonyliron complexes via cyclopropane ring opening, hydrogen migration and coordination to iron. Reaction with the latter substrate gives 2‐cyclopropyl‐1,3‐pentadienetricarbonyliron in similar fashion, and, in addition, 3‐(1′‐propenyl)‐cyclohex‐2‐enone tricarbonyliron derived from the opening of the second ring coupled with carbon monoxide insertion. The cyclopropane ring serves as a two π‐electron donor in these reactions, and the vinylcyclopropane system emerges as a novel source of four π‐electrons which are available to coordination in direct analogy to reactions of f

ISSN:0021-2148    

DOI:10.1002/ijch.197200079

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

Abstractp‐Tri‐methylsilylphenethylamine and 1‐p‐trimethylsilyphenyl‐1‐amino‐4‐dimethylamino‐butane were reacted with 9‐chloroacridines to give the corresponding N‐substituted 9‐amino acridines, which inhibited the growth of several

ISSN:0021-2148    

DOI:10.1002/ijch.197200080

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractUltraviolet spectra show that hypoxanthine and 6‐thiopurine are present in aqueous solution predominantly as 1H, 9H‐tautomers. However, a 3‐methyl group causes the imidazole ring to assume the 7‐NH form. The sequence of anion formation in hypoxanthine is 9(7) → 1 and in 6‐thiopurine 1 → 9(7). The NMR spectra suggest that the mono‐anion of hypoxanthine is a mixture of tautomers. Protonation always takes place in the imidazole ring, with the exception of 3‐methyl derivatives. In the latter, formation of mono‐cations involves th

ISSN:0021-2148    

DOI:10.1002/ijch.197200081

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractEnergy profiles and molecular binding number (MBN) were calculated for purine and its mono‐protonated forms by the CNDO/2 algorithm. Total energy indicates that the 3,7‐species is the most stable among the protonated isomers, being insignificantly more stable than the 1,7‐analogue. Electronic energy suggests that proton may preferentially be attached to position 3. Charge densities are presented by both Mulliken's population method and C

ISSN:0021-2148    

DOI:10.1002/ijch.197200082

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractMethyl‐lithium gave with 1‐phenyl‐1‐propyne and 1‐phenyl‐1‐butyne preferentially the products of monometalation although dimetalation of these compounds is faster than monometalation when butyl‐lithium is used. The product of protonation of dilithiophenylbutyne depends on the condition of the reaction. In the presence of starting material, 4‐phenylbut‐2‐yne and in its absence, 1‐phenylbuta‐1,2‐diene is obtained. Alkylation, silylation and protonation of the lith

ISSN:0021-2148    

DOI:10.1002/ijch.197200083

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY