摘要:

AbstractBy treatment with potassium amide in liquid ammonia at −75°, 4‐chloro‐5‐cyano‐6‐phenylpyrimidine is converted into 4‐amino‐5‐cyano‐6‐phenylpyrimidine; 1‐amino‐2,2‐dicyano‐1‐phenylethene is formed as a minor reaction product. Evidence is presented, using the labelled compounds 4‐chloro‐5‐cyano‐6‐phenyl‐[1(3)‐15N]‐ and 4‐chloro‐5‐[14C]cyano‐6‐phenylpyrimidine thatithe conversion into the corresponding 4‐amino compound proceeds completely according to the ANRORC mechanism,iithe14C‐cyano function remains nearly completely extranuclear. The synthesis of the15N‐ a

ISSN:0165-0513    

DOI:10.1002/recl.19730920502

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe synthesis of the fully protectedN‐terminal decapeptide of human growth hormone, Boc‐Phe‐Pro‐Thr(Bzl)‐Ile‐Pro‐Leu‐Ser(Bzl)‐Arg(NO2)‐Leu‐Phe‐OMe (HGH 1‐10) by the repetitive excess mixed anhydride (REMA) method is described.Starting from Phe‐OMe this sequence was synthesized in a stepwise manner in an overall yield of 59%. In the coupling of Boc‐Ile to Pro‐Leu‐Ser(Bzl)‐Arg‐(NO2)‐Leu‐Phe‐OMe the isobutoxycarbonyl derivative of the amino‐component was isolated. This problem of reaction on the undesirable side of the mixed anhydride in the couplings to proline‐peptides was circumvented by the coupling of dipeptides,viz. Boc‐Ile‐Pro and Boc‐Phe‐Pro. Also a larger peptide fragment, ZPhe‐Pro‐Thr‐Ile‐Pro (HGH 1‐5), was conveniently coupled to theC‐terminal pentapeptide. Synthesis of Boc‐Leu‐Ser(Bzl)‐Arg(NO2)‐Leu‐Phe‐OMe (HGH 6‐10) was performed with and without intermediate purification. It was found that the yield was higher when no purifications were applied.HGH 6‐10 was compared with the corresponding peptide synthesized by the solid phase method. Both products were found to be identical with regard to melting point, optical rotation and chromatographic behaviour. The decapeptide, on deprotection, showed identical chromatographic behaviour with a product obtained by the solid phase method. The optical rotations showed a small difference;

ISSN:0165-0513    

DOI:10.1002/recl.19730920503

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractN,N‐Dialkyl‐2‐(arylmethoxy)‐ orN,N‐dialkyl‐2‐(diarylmethoxy)acetamides were found to undergo a Wittig rearrangement under the influence of bases such as sodium hydride to form eitherN,N‐dialkyl‐3‐aryl‐ or 3,3‐diaryllactamides. When the diarylmethoxy group was asymmetric, the rearrangement resulted in diastereoisomeric reaction products.Orthosubstitution in one or both aryl rings altered the course of rearrangement with the result that additionally, or even exclusively,p‐benzylmandelic amide derivatives were formed. Not only rearrangement products but also byproducts like diaryl ketone, diarylmethane and tetraarylethane were formed. The formation of the latter compound would indicate that radicals are somehow involved in the reaction mechanism. To date, attempts to obtain more than circumstantial evidence for such a mechanism have failed. In several cases byproducts with the structure of a substitutedp‐benzylbenzoic acid were isolated. These acids were found to arise from the above “pararearrangement” products by further decomposition under the influence of the basic catalyst. The scope of the reaction was explored by studying the rear

ISSN:0165-0513    

DOI:10.1002/recl.19730920504

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractKinetics of the primary cracking reactions occurring in the high pressure thermal hydrogenolysis of 1, 2, 3, 4‐tetrahydronaphthalene (tetralin) and hydrindene (indan) were studied in a flow reactor at temperatures from 460° to 540°C, total pressures from 10 to 160 atm. and molar ratios of hydrogen‐to‐hydrocarbon from 2 to 100.As primary cracking products from tetralin were identifiedn‐butylbenzene, styrene, ethylene, 1‐methylindan ando‐propyltoluene.From indan were obtainedn‐propylbenzene, toluene, ethylene,o‐ethyl‐toluene,o‐xylene and methane.Chain mechanisms are proposed for the reactions leading to these primary products.The theoretical rate equations derived from these are in good agreement with

ISSN:0165-0513    

DOI:10.1002/recl.19730920505

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe conformational chair‐chair equilibrium intrans‐6‐alkyl‐4‐methyl‐, andtrans‐6‐alkyl‐4‐phenyl‐1,3‐dioxanes has been determined by NMR spectroscopy. The equilibrium constant was calculated with the aid of coupling constants, and involved the use of model compounds. The experimental order of conformational preferences of the alkyl groups is i‐Pr>Et>Pr ≈︁ i‐Bu ≈︁ neoPe ≈︁ Me, in agreement with theory. Base catalyzed epimerization ofcis‐, andtrans‐6‐methyl‐4‐phenyl‐1,3‐dioxane, together with the conformational equilibrium in thetransisomer, investigated here allows the evaluation of ΔG°303values

ISSN:0165-0513    

DOI:10.1002/recl.19730920506

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractProlonged treatment of μ‐dichloro(π‐benzene)ruthenium(II) with hydrogen in dimethylformamide solution results in the formation of a catalyst allowing of a rapid and homogeneous hydrogenation of compounds containing alkenic bonds. The hydrogenation rates of 1‐alkenes, cycloalkenes, and alkenes containing functional groups have been studied quantitatively.The kinetics of the hydrogenation of cyclooctene can be described by the rate expression:R=A[Ru] [H2][S]/(B + C[S])where A, B and C are constants and [Ru], [H2] and [S]the catalyst, hydrogen and alkene concentration, respectively. From the hydrogenation data obtained for cyclooctene, the activation energy was calculated to be ca 6 kcal. mole−1.The results of experiments involving isotopic exchange with molecular hydrogen‐deuterium gas mixtures and the incorporation of deuterium during the deuterogenation of cyclooctene suggest that the actual active catalytic species is (π

ISSN:0165-0513    

DOI:10.1002/recl.19730920507

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractA description of two alternative routes (Schemes 1 and 2) for the synthesis of the title compound (I) is given. Only the second route resulted in the formation of the two diastereomers of I. The physical properties of both isomers are given. The reacemization is discussed.

ISSN:0165-0513    

DOI:10.1002/recl.19730920508

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe occurrence of intramolecular 1,4‐hydride shifts from alkane carbon to oxocarbonium carbon in acyl cations has been demonstrated in the long‐lived 4‐methyl‐ and 3,4‐dimethylpentanoyl cations in FSO3HSbF5. Strong, though not conclusive evidence has been obtained for an intramolecular 1,5‐hydride shift in the hexanoyl cation. Attempts to observe a 1,5‐hydride shift in 5‐methyl‐hexanoyl ion were unsuccessful owing to the occurrence of side reactions; in FSO3HSbF5this cation undergoes intermolecular hydride abstraction. The 1,4 shifts are much faster than 1,2‐ or 1,3‐hydride shifts to oxocarbonium carbon, as demonstrated by the absence of the latter reactions, under comparable conditions, in the pentanoyl, 3‐methylpentanoyl and 2‐methylbutanoyl ions. The differences in the relative rates of 1,2‐ 1,3‐ and 1,4‐hydride shifts between oxocarbonium an

ISSN:0165-0513    

DOI:10.1002/recl.19730920509

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractIn the presence of zeolites, cyclopropenes can cyclodimerize to give tricyclo‐[3.1.0.02,4]hexanes, isomerize to yield 1,3‐butadienes or polymerize. Which pathway is chosen depends on the structure of the cyclopropene and on the nature of the zeolite. This novel method for the cyclodimerization of cyclopropenes is superior to known procedures of preparing tricyclohexanes. It constitutes a unique example of a reaction being forced to proceed in a certain direction by spatial restriction of the reacting molecu

ISSN:0165-0513    

DOI:10.1002/recl.19730920510

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe solubilities of (n‐C4H9)4NI, (n‐C4H9)4NClO4, (n‐C4H9)4NNO3and (n‐C4H9)4NSCN in liquid ammonia at −37°C were determined gravimetrically. Specific conductances of the saturated solutions were measured. Tetra‐n‐butyl‐ammonium nitrate is recommended as supporting electrolyte for electrochemical experiments i

ISSN:0165-0513    

DOI:10.1002/recl.19730920511

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY