摘要:

AbstractIn the present investigation, we have measured the secondary deuterium isotope effects in borohydride addition reaction for a serie of cyclohexanones, both hindered and unhindered. We observed an inverse isotope effect,kH/kD<1.00 for those ketones; these inversions of the isotope effects are discussed in terms of torsional effects and hyperconjugative factor.

ISSN:0165-0513    

DOI:10.1002/recl.19851040902

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe co‐oxidation reaction between isoprene, some aromatic thiols and molecular oxygen is described. The product distribution, in relation to the nature of the aromatic thiol used, is examined. Steric and electronic factors are discusse

ISSN:0165-0513    

DOI:10.1002/recl.19851040903

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractPhenylacetylene can be dimetallated in two ways.o‐K‐C6H4‐C  C ‐ Li is formed by treating phenylacetylene at −70°C with two equivalents of butyllithium and one equivalent of potassiumtert‐butoxide in a mixture of tetrahydrofuran and hexane. The dimetallation with BuLi‐N,N,N′, N′‐tetramethylethanediamine (TMEDA) affords a mixture of about 15% (m+p)‐Li‐C6H4‐C  C Li and 85%o‐Li‐C6H4‐C  C‐Li.Ortho‐K‐C6H4‐C  C‐Li can be transformed into the dilithio or di‐Grignard derivatives by addition of anhydrous lithium bromide or magnesium bromide etherate. Reaction of the dilithio derivative with elemental selenium and tellurium, followed by successive addition oftert‐butyl alcohol and hexamethylphosphoric triamde (HMPT), gives benzo[b]selenophene and benzo[b]tellurophene in good yields.Regiospecific functionalization of the nucleus via dimetal derivatives succeeds in the case of alkylation, halogenation, sulfenylation and acylation (with dimethylformamide and dimethylacetamide). Trimethylchlorosilane, chloromethyl methyl ether, aldehy

ISSN:0165-0513    

DOI:10.1002/recl.19851040904

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA combination of11B and13C NMR spectroscopy with several model compounds has been used to elucidate the nature of the ester formation between borate and D‐mannitol, D‐glucitol, D‐fructose and D‐glucose in aqueous solution at pH 6‐12 and at 25 °C. At high carbohydrate/borate ratios, D‐mannitol shows the selective formation of bis(D‐mannitol) 3,4:3′4′ ‐borate, whereas D‐glucitol forms a mixture of six different bis(D‐glucitol) borate esters involving both 2,3‐ and 3,4‐dihydroxyl moieties. Bis(D‐fructose) and bis(D‐glucose) borate esters consist of pairs of diastereomers of the 2,3‐β‐and 1,2‐α‐furanose moieties, respectively. At low carbohydrate/borate ratios, mono‐, di‐ and, sometimes, tri‐borate esters are formed,e.g.mixture of α‐D‐glucofuranose 1,2:3,5‐diborate and α‐D‐glucofuranose 1,2:5,6‐diborate for D‐glucose and a mixture of β‐D‐fructopyranose 1,2:4,5‐diborate and β‐D‐fructopyranose 2,3:4,5‐diborate for D‐fructose. The overall stability constant for the borate di‐esters of D‐mannitol, D‐

ISSN:0165-0513    

DOI:10.1002/recl.19851040905

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

Abstract1,2‐O‐Carbonyl‐4,6‐O‐ethylidene‐ (4), 4,6‐O‐benzylidene‐1,2‐O‐carbonyl‐ (6) and 1,2‐O‐carbonyl‐4,6‐O‐(p‐methoxybenzylidene)‐α‐D‐galactopyranose (7) were prepared from the corresponding 4,6‐O‐alkylidene‐D‐galactopyranoses (1, 2and3) by reaction with 1,1′‐carbonyldiimidazole and the isomerization of4, 6and7into the 3,4‐acetals8, 10

ISSN:0165-0513    

DOI:10.1002/recl.19851040906

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe syntheses of the title compound and of some ester derivatives are described. These norprogesterone derivatives show interesting progestational activities.

ISSN:0165-0513    

DOI:10.1002/recl.19851040907

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe porphyrins1a‐gwere synthesized. In CDCl3solution1aand1boccur to an important extent in a folded conformation, as is indicated by an upfield shift of 2‐3 ppm for the tosylprotons in the1H NMR spectrum. For compounds with longer chains or an ester instead of a sulfonyloxy group the upfield shift is much smal

ISSN:0165-0513    

DOI:10.1002/recl.19851040908

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19851040901

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY