摘要:

AbstractThe protonation and deprotonation rates of the coordinated amide groups in the Ni2+and Cu2+complexes of 3,7‐diazanonanediamide (DANA) and in the Cu2+complex of 3,7‐diazanonane‐N,N′‐diethylamide (DANEA) have been studied by stopped‐flow techniques. For the interconversion M(H−2L) ⇌ ML, two consecutive reactions are observed in the case of Cu2+with DANA or DANEA, whereas there is only one reaction for Ni2+with DANA. Cu(H−2DANEA) is unusually labile, indicating a strong interaction between the N‐ethyl groups. The conversion of the O‐ into the N‐coordinated amide groups in NiDANA2+is 25 times slower than in CuDANA2+. In the case of Ni2+this excludes a step with water substitution, which is involved in one of the reaction paths observed for the Cu2+complexes, since the rates of water exchange differ by a factor of 10

ISSN:0018-019X    

DOI:10.1002/hlca.19740570702

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

Abstractt‐Butyl (E)‐O‐acetyl‐Δ2‐anhydromevalonate could be prepared. by aReformatskyreaction of 4‐acetoxybutan‐2‐one andt‐butyl bromoacetate. Condensation of its activated derivatives with the diketopiperazine of N5‐hydroxy‐L‐ornithine led to di‐O‐acetyl dimerumic acid, which could be transformed, by ammonolysis, to dimerumic acid, identical with the natural compound. The corresponding acetohydroxamic acid, prepared by acetylation of the diketopiperazine, was identical wi

ISSN:0018-019X    

DOI:10.1002/hlca.19740570703

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

Die Reaktivität von «harten» und «weichen» Nucleophilen (Hydroxid, Methoxid, Dimethylamin, 2‐Imino‐3‐äthyl‐benzthiazolin, Triphenylphosphin, Carbanionen, Azid, Cyanid, Arylsulfinat, 3‐Äthyl‐benzthiazolin‐2‐yliden, 3‐Methyl‐benzthiazolinon‐(2)‐hydrazon) gegenüber dem ambidenten elektrophilen 2‐Azido‐3‐äthyl‐benzthiazolium‐Ion wird untersucht. Das reaktive Verhalten lässt sich m

ISSN:0018-019X    

DOI:10.1002/hlca.19740570704

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

Abstract3‐Hydroxy‐ceph‐3‐em‐esters5 a–c, versatile intermediates for the preparation of new β‐lactam antibiotics, were obtained by ozonolysis of the corresponding 3‐methylidene‐esters3 a–c. Reduction and elimination gave the 3‐unsubstituted ester13; derivatives16 a–cand20–22resulted from O‐alkylation. The 3‐methoxy‐esters16 a–cwere converted into the corresponding acids23 a–d. Several other transformations of

ISSN:0018-019X    

DOI:10.1002/hlca.19740570705

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractOn treatment with ammonia and benzaldehyde the benzalisoxazolone3does not give the aminoketone7as assumed bySperoni[1] but a product which has been shown to be identical with the enamine8prepared byRied&Czack[4] from ethyl oximinoacetoacetate and benziminoethyl ether. Authentic aminoketone7was synthesized in a three‐step procedure starting from the aminonitrile19. Conversion of7into the bromacetyl derivative23and subsequent treatment with hexamethylene‐tetramine yielded the isoxazolodiazepine24. Methylation of24with diazomethane produced predominantly the N‐methyl derivative1along with a small amount of the O‐methyl com

ISSN:0018-019X    

DOI:10.1002/hlca.19740570706

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractThe activation parameters for the oxidation of 13 secondary alcohols with chromic acid have been determined. Application of a statistical treatment ofExner[9] shows that the reactions are isoentropic with an average entropy of activation (ΔS≠) of −24.0

ISSN:0018-019X    

DOI:10.1002/hlca.19740570707

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractVarying amounts of water have been solubilized in a micelle solution of sodium di‐2‐pentyl–sulfoscuccinate in benzene and the complex permittivity has been observed in the range 200 KHz to 10 MHz. Part of a dielectric dispersion is seen, which extends to higher frequencies with a broad distribution of relaxation times. Due to association processes, the static dielectric increment is found to vary non‐linearly with hydrated micelle concentration and with the amount of solubilized water, whereas a linear variation with micelle concentration is found if no water is added. These effects are explained on the assumption that part of the solubilized water increases the dipole moment of the micelle.Additionally, at higher water concentrations, a sudden increase in the conductivity of the solution is observed, which is taken to indicate a conformational change of the solubilized

ISSN:0018-019X    

DOI:10.1002/hlca.19740570708

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractOn treatment with diazomethane, 2,4,6/3,5‐penta‐acetoxy‐cyclohexanone(penta‐O‐acetyl‐myo‐inosose‐2 or ‐scyllo‐inosose) gave only a spiroepoxide. In contrast, replacement of diazomethane by higher diazoalkanes furnished a mixture of alkylspiroepoxides and of ring expansion products (cycloheptanone derivatives). The configuration and the reactions of the spiro‐epoxi

ISSN:0018-019X    

DOI:10.1002/hlca.19740570709

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractOn treatment with higher diazoalkanes, 2,4,6/3,5‐penta‐acetoxy‐cyclohexanone (penta‐O‐acetyl‐myo‐inosose‐2 or ‐scyllo‐inosose) afforded by ring expansionall‐trans‐penta‐acetoxy‐C‐alkyl‐cycloheptanones, which by deacylation were converted to hemiacetals. The reactions with diazoalkanes of the penta‐acetoxy‐inosose in the presence of aluminium chloride and of the free inosose in water solution have also been studied. The structure, the configuration, and, in some cases, the conformation of the new compounds have been established and some of their reactions have been investigated. The mechanisms of formation of the ring expansion products and of the concomitant

ISSN:0018-019X    

DOI:10.1002/hlca.19740570710

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY

摘要:

AbstractIn contrast to butyllithium, ethylmagnesium‐bromide reacts with 1‐phenyl‐pyrazole exclusively by deprotonation, at theorthoposition of the phenyl‐ring. With nitriles the intermediate 2‐(1‐pyrazolyl)‐phenylmagnesiumbromide gave good to excellent yields of 1‐(2‐aroyl or 2‐hetaroyl‐phenyl)‐pyrazoles (Table 1, compounds5a–5i); with ketones the corresponding methanol derivatives (Table 2, compounds6a–6c) were found, whilst CO2yielded the corresponding 1‐(2‐carboxyphenyl)‐pyrazole (3). Surprisingly enough, 1‐(o‐bromo‐phenyl)‐pyrazole and magnesium did not yield a single product, but a mixture of 3 compounds, which on reaction with 4‐benzoy

ISSN:0018-019X    

DOI:10.1002/hlca.19740570711

出版商:WILEY‐VCH Verlag GmbH    

年代:1974

数据来源: WILEY