ISSN:0165-0513    

DOI:10.1002/recl.19881070302

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe chloro‐ and dichlorophenols have been sulfonated with sulfuric acid and with SO3in aprotic solvents. In the sulfonations with concentrated aqueous sulfuric acid, the sulfonic acid isomer distribution is determined mainly by theortho‐andpara‐directing and activating effect of the hydroxy substituent; this is also the determining factor in the aprotic sulfonations using up to 1.0 equiv of SO3. Upon using larger amounts of SO3, the sulfonation isomer distribution is increasingly determined by additional sulfonation of the corresponding phenyl hydrogen sulfate, of which the ‐OSO3H substituent is deactivating and mainlypara‐(and furtherortho‐) directing.The sulfuric acid sulfonation of (2,3‐, 2,4‐ and 3,4‐dichlorophenoxy)acetic acid leads to the exclusive formation of the 4‐, 6‐ and 6‐sulf

ISSN:0165-0513    

DOI:10.1002/recl.19881070303

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractAll‐trans‐5‐demethylretinal and its 5‐2H, 7‐2H and 5,7‐2H2isotopomers have been synthesized by means of a new and simple scheme. Using photochemistry, the 9‐, 11‐ and 13‐cis, as well as the 9,13‐ and 11,13‐di‐cisisomers, were obtained. The structures were established by mean

ISSN:0165-0513    

DOI:10.1002/recl.19881070304

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractDL‐1‐Amino‐3‐buten‐2‐ol HH2CCH‐CH(OH)‐CH2NH2has been synthesized in a satisfactory overall yield by reduction of the protected cyanohydrin H2CCH‐CH(OR)‐CN [R = ‐CH(CH3)OC2H5] with aluminum hydride, followed by removal of the protecting group with aqueous hydrochloric acid and treatment with potassium hydroxide. The amino alcohol is a key intermediate in a synthesis of the antithyroid factor

ISSN:0165-0513    

DOI:10.1002/recl.19881070305

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractMetal carbonyl cluster complexes containing iron, phenylphosphido units and another metal (Ni, Pd, Pt, Co, Hg) have been prepared by reactions of (μ‐PhPLi)2Fe2(CO)6with metal halides and (μ‐PhPH)2Fe2(CO)6with zerovalent metal comp

ISSN:0165-0513    

DOI:10.1002/recl.19881070306

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe absorption and emission spectra of the mixed nitrates Ln2Mg3(NO3)12·24H2O (Ln = La, Ce, Eu, Gd) are reported. The interaction between the 4felectrons of the Ln3+ion and the nitrate group is unexpectedly strong. This is apparent from a strong additional absorption in the case of Ce3+and strong cooperative vibronic emission and absorption lines in the case of Eu3+

ISSN:0165-0513    

DOI:10.1002/recl.19881070307

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe four‐membered cyclic nitrones1and2react with dimethyl acetylenedicarboxylate to give the corresponding cycloadducts3,4. Upon reaction of2awith phenylacetylene, the 5′‐substituted isoxazoline derivative5was obtained. Reaction of2awith methyl propynoate yielded a 1:4 mixture of the 4′‐ and 5′‐cycloadductsδ,7and6, respectively. Reaction of2a‐cwith N‐phenylmaleimide and of2awith diethyl maleate yielded the corresponding azeto[1,2‐b]pyrrolo[3,4‐d]isoxazole derivatives,8and9, respectively. The exclusive formation of theexo‐conformation of the cycloadducts was unequivocally proven by X‐ray analysis of8a. Reaction of2awith methyl 2‐propenoate (methyl acrylate) and 3‐buten‐2‐one (methyl vinyl ketone) gave regio‐ and stereoselectively the correspondingexo‐5′‐isoxazolidine cycloadducts,10and11, respectively. The stereochemistry of the cycloadducts was deduced from the1H NMR data. Both alkyne and alkene dipolarophiles approach the four‐membered cyclic nitrones from the sterically less hindered side, resulting in a (regio‐ and) stereose

ISSN:0165-0513    

DOI:10.1002/recl.19881070308

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractStudies of ring opening of chlorocyclotrigermazanes in cycloaddition reactions with the nitrones phenyl‐ andtert‐butylbenzylideneamine N‐oxide, catalysed byLewisbases (HMPA) orLewisacids (ZnCl2; M(CO)6; M(CO)5·THF, M = Cr, W), show that hexachlorocyclotrigermazanes are much less reactive than the corresponding methylcyclogermazane. The decreased reactivity is attributed to the tendency of the electron‐attracting chlorine atoms to promote the “back‐donation” of electrons from nitrogen to germanium, thereby rendering the Ge‐N bond less polar and therefore less susceptible to coordination (either withLewisacids orLewisbases) and attack by polar reagents such as ca

ISSN:0165-0513    

DOI:10.1002/recl.19881070309

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe reaction of 1,3‐dibromocyclobutane (5) and of 1,3‐dibromocyclopentane (6) with magnesium in diethyl ether has been investigated. The corresponding 1,3‐di‐Grignard reagents7(<9%) and12(〉〉45%), respectively, were obtained. Compound12decomposes to (2‐cyclopentenyl)magnesium bromide (13) with a half‐life of 5 h. The yields and stabilities of7and12are br

ISSN:0165-0513    

DOI:10.1002/recl.19881070310

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe synthesis and characterization of transition‐metal coordination compounds with the novel, tetradentate ligand 1,6‐bis(5‐methyl‐4‐imidazolyl)‐2,5‐dithiahexane (abbreviated bidhx) are described. The nitrates have the general formula M(bidhx)(NO3)2·nH2O (M = Co, Ni, Cu, Zn; n = 0 ‐ 2). With the isothiocyanate anion, monomers M(bidhx)(NCS)2containing Co, Ni and Zn and Cu(bidhx)(NCS)(NO3) as well as a dimer Cu2(bidhx)(NCS)3were isolated. In all compounds, bidhx acts as a tetradentate ligand with both thioether sulfurs and both imidazole nitrogens coordinating. All compounds are six‐coordinated in a distorted octahedral geometry, although, for the copper mixed‐anion compound, a five‐coordination in a square pyramidal geometry may also be possible. A single crystal of [Ni(NCS)2(bidhx)](MeOH) was used in a structure determination: monoclinic, space group C2/c, a = 13.0516(7) Å, b = 16.383(1) Å, c = 10.3758(9), Å, β = 101.095(6) deg, Z = 4 and T = 293 K. The structure was solved using heavy‐atom techniques and refined by least‐squares methods to an R value of 0.0508. The nickel ion is in a distorted octahedral environment with the two thiocyanates in acisposition. The nickel to nitrogen distances are ca. 2.04 Å; the nickel to

ISSN:0165-0513    

DOI:10.1002/recl.19881070311

出版商:WILEY‐VCH Verlag    

年代:1988

数据来源: WILEY