ISSN:0165-0513    

DOI:10.1002/recl.19851041002

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe asymmetric phase‐transfer‐catalysed (PTC)Darzenscondensation of aldehydes and ketones with the chiral reagents (S)‐( ‐ )‐N‐(chloromethylsulphonyl)‐2‐(methoxymethyl)pyrrolidine (2), (S)‐( ‐ )‐tert‐butylN‐(chloromethylsulphonyl)prolinate (4) and ( + )‐O‐methyl‐N‐(chloromethylsulphonyl)ephedrine (6), using triethylbenzylammonium chloride (TEBA) as the phase‐transfer catalyst, to give optically active diastereomeric α,β‐epoxy sulphonamides (oxiranesulphonamides), is described. Of the three chiral reagents used,2was found to be the most effective, imparting an asymmetric induction of up to almost 50%, as assessed by Eu(fod)3‐resolved1H NMR spectra. The stereochemical course

ISSN:0165-0513    

DOI:10.1002/recl.19851041003

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe synthesis of glucuronides derived from mianserin and its 6‐aza analogue (Org 3770) is described. Several methods were investigated. The most successful approach was the coupling of 1,2,3,4,10,14b‐hexahydro‐8‐hydroxy‐2‐(trifluoroacetyl)dibenzo[c,f]pyrazino[1,2‐a]azepine or its 6‐aza analogue with methyl [trichloroethanimidoyl 2,3,4‐tris‐O‐(phenylmethyl)‐α‐D‐glucopyranosid]uronate catalyzed by BF3. Fully protected glycosides were obtained as diastereomeric β/α mixtures. After deprotection the glucuronides of 2‐demethylmianserin and 2‐demethyl‐Org 3770 were synthesized. The correspondingN(2)‐methyl analogues were obtained by reductive methylation. The synthetic β‐glucuronides were identical with the isola

ISSN:0165-0513    

DOI:10.1002/recl.19851041004

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

Abstract5,6‐O‐Isopropylidene‐L‐gulono‐ and ‐D‐mannono‐1,4‐lactones are converted into 2‐(dimethylamino)‐1,3‐dioxolane derivatives on treatment withN,N‐dimethylformamide dimethyl acetal in chloroform with azeotropic removal of the methanol thus formed. Quaternisation of the products with iodomethane, followed by thermal decomposition yields the corresponding C(4)‐substituted enantiomeric butenolides. Some aspects of the reactions, the characterisation of the products, and further tr

ISSN:0165-0513    

DOI:10.1002/recl.19851041005

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe photochemical rearrangement of the two 2‐(2‐alkenyl)‐2‐(1‐cyclopentenyl)cyclopentanones (E)‐1aand (E)‐2ahave been studied under conditions of both direct (λ 300 nm) and tripletsensitized irradiation in order to determine the applicability of 2‐alkenyl moieties as intramolecular quenchers of the lowest excited triplet states of the β,γ‐enone chromophore.The β,γ·γ′,δ′‐dienone (E)‐1a, upon direct irradiation, exhibits a reversible 1,3‐acyl shift (1,3‐AS) leading to an eventual photostationary state {[(E)‐1a]/[(E)‐1b]}pss= 4.0 ± 0.8, whereas triplet photosensitization of (E)‐1agives the ODPM isomer (E)‐1c. Both processes occur without (E)‐(Z) isomerization of the 2‐butenyl side‐chain. Direct irradiation of (E)‐2ayields, albeit very inefficiently, the 1,3‐AS compound (E)‐2b(Φ<0.001) as the primary product which, upon electronic excitation, forms, in competing reactions, (E)‐2a(Φ = 0.18) and (Z)‐2b(Φ = 0.035). Upon triplet photosensitization of both (E)‐2aand (E)‐2b, only (E)‐(Z) isomerization of the styryl side‐chain is observed. The eventual photostationary state in the direct irradiation equals {[(E)‐2a]/[(Z)‐2a]/[(E)‐2b]/[(Z)‐2b]}pss=(33± 1)/(33 ± 1)/(17 ± 1)/(17 ± 1).The differences in photochemical behaviour of the β,γ·γ′,δ′‐dienone substrates and their 1,3‐AS products are discussed with special emphasis being placed upon the triplet energies of the 2‐alkenyl chromophores relative to those of the β,γ‐enone chromophores and the occurrence of

ISSN:0165-0513    

DOI:10.1002/recl.19851041006

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19851041001

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY