摘要:

AbstractThe effects on pKof 3‐, 4‐, and 3,5‐(di)alkyl groups in all‐equatorial cyclohexane‐carboxylic acids are examined in detail. They show quantitatively the same anomalies as in the benzoic acids. Similar characteristics have been found for cyclohexanecarboxylic acids with carboxyl axial, for cyclohexaneacetic acids, β‐tert‐butylpropionic acid, γ‐tert‐butylbutyric acid, andtrans‐2‐(trimethylsilyl)cyclohexanecarboxylic acid. Substituent effects from the 2 and α positions usually show the presen

ISSN:0165-0513    

DOI:10.1002/recl.19901090902

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe synthesis and characterization of cyclopent[hi]aceanthrylene, a novel dicyclopenta‐fused polycyclic hydrocarbon, are described. The key step is the reductive double alkylation of anthracene by lithium bromoacetate in liquid ammonia givingcis‐9,10‐dihydroanthracene‐9,10‐diacetic acid in good yield. Lithium bromoacetate is a better alkylating agent than the sodium iodoacetate form

ISSN:0165-0513    

DOI:10.1002/recl.19901090903

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractStereoselective β‐glycosidation of 1,3,4‐tri‐O‐benzyl‐5‐O‐pivaloyl‐D‐ribitol, prepared from L‐ribose, with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranose gave, after protecting‐group manipulations, the properly protected terminal and non‐terminal units. Elongation (2 ×) of the terminal unit with the incoming non‐terminal unit could be accomplished using the bifunctional phosphorylating reagent, bis(l‐benzotriazolyl) 2‐chlorophenyl phosphate. The trimeric unit thus obtained was condensed, using the same phosphorylating reagent, with the spacerN2‐(benzyloxycarbonyl)‐N1‐(3‐hydroxypropyl)glycinamide, to give, after complete deblocking,

ISSN:0165-0513    

DOI:10.1002/recl.19901090904

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractTheN‐alkylation of aminopolyols and amino acids by a Michael‐type addition with maleate or fumarate in aqueous medium occurs readily at 90°C. Maleate reacts faster than fumarate by virtue of the higher free energy of the ground state. For a series of amino compounds, the second‐order rate constants are related to the nucleophilicity of the nitrogen and the steric hindrance involved. SubsequentN‐alkylation of aminohydroxyl compounds and LaIII‐ion‐catalyzedO‐alkylation of hydroxyl groups with maleate is shown to be a promising way to synthesize new ch

ISSN:0165-0513    

DOI:10.1002/recl.19901090905

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

Abstract(S)‐2‐Chloropropanoyl chloride reacts cleanly with α‐substituted α‐hydroxy acids (or esters) to giveO‐acyl derivatives, which can be used for the establishment of optical purities of the acids or t

ISSN:0165-0513    

DOI:10.1002/recl.19901090906

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractA new and convenient route for the synthesis of the thieno[3,2‐e]indolizines4a,b,d, the thieno[2,3‐c]quinolizine4eand their [1]benzothieno analogues9a,bis presented. Reaction of the (dialkylamino)thiophenes1, 5and7with (methoxymethylene)malononitrile (2) gives the Michael adducts3, 6and8. Heating of3and8in refluxing 1‐butanol gives the cyclized products4and9. This cyclization proceeds via a 1,5 hydrogen shift, followed by an intramolecular addition of the carbanion to the iminium double bond in the intermediate10formed. The scope and limitations of this approach are disc

ISSN:0165-0513    

DOI:10.1002/recl.19901090907

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractSulfonation of norbornene1with the SO3‐dioxane complex affords the β‐sultone2, which rearranges at room temperature to the γ‐sultone3. Reaction of1with 2 equiv of SO3‐nitromethane yields the carbyl sulfate4. Carbocations arenotinvolved in the formation of either the β‐sultone or the ca

ISSN:0165-0513    

DOI:10.1002/recl.19901090908

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractCyclopalladatedN,N‐dimethylbenzylamine complexes can be oxygenated withtert‐butyl hydroperoxide to the corresponding phenolates in good yield (>80%); the rate of oxygenation is highly enhanced by increasing the nucleophilicity of the metal center or by addition of a vanadium catal

ISSN:0165-0513    

DOI:10.1002/recl.19901090909

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19901090910

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19901090901

出版商:WILEY‐VCH Verlag    

年代:1990

数据来源: WILEY