摘要:

AbstractThe synthesis of oligonucleotides containing 7‐(2‐deoxy‐β ‐D‐erythro‐pentofuranosyl)adenine (N7Ad;1) is described. Compound1was obtained from the precursor 4‐amino‐1H‐imidazole‐5‐carbonitrile 2‐deoxyribonucleoside6and was found to be much more labile than Ad. TheN6‐benzoyl protecting group (see8) destabilized the N‐glycosylic bond further and was difficult to remove by NH3‐catalyzed hydrolysis. Therefore, a (dimethyl‐amino)methylidene residue was introduced (→9). Amidine9was blocked at OHC(5′) with the dimethoxytrityl residue ((MeO)2Tr), and phosphonate4as well as phosphoramidite5were prepared under standard conditions. Phosphonate4was employed in solid‐phase oligonucleotide synthesis. Homooligonucleotides as well as self‐complementary oligonucleotides were prepared. The oligomer d[(N7A)11‐A] (11) formed a duplex with d(T12) (13). Antiparallel chain polarity and reverseWatson‐Crickbase pairing was deduced from duplex formati

ISSN:0018-019X    

DOI:10.1002/hlca.19940770302

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe reaction of 2‐(1‐phenylvinyl)aniline and 4‐chloro‐2‐(1‐phenylvinyl)aniline with acetophenone derivatives, 1‐(naphthalen‐1‐yl)ethanone and 1‐(furan‐2‐yl)ethanone in toluene at 110–115° with toluene‐4‐sulfonic acid as a catalyst leads in good‐to‐excellent yields to the 2,2‐disubstituted 1,2‐dihydro‐4‐phenyl‐quinolines1–18(Scheme 1, Table). The structure of the new racemic 1,2‐dihydroquinolines1–18is determined by NMR spectroscopy. A reaction mechanism proceedingviaa 6π‐electrocyclic rearrangement of 2‐(1‐phenylvinyl)anils19as the key step is proposed for the formation of these compounds (Scheme 1). The scope and

ISSN:0018-019X    

DOI:10.1002/hlca.19940770303

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractA crude hydrate6and a crystalline hemiacetal7of glyoxylamide4were prepared from crotonamide5(Scheme 2). Particularly hemiacetal7, but also6and the ‘dimer’8(obtained from7) may serve as homochiral auxiliaries. The structure of8was determined by X‐ray analysis. By arenesulfonyl halides, tryptimines12–14of4were diastereoselectively transformed into spirotricycles15

ISSN:0018-019X    

DOI:10.1002/hlca.19940770304

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe 2′‐deoxyisoguanosine (1) was synthesized by a two‐step procedure from 2′‐deoxyguanosine (5). Amination of silylated 2′‐deoxyguanosine yielded 2‐amino‐2′‐deoxyadenosine (6) which was subjected to selective deamination of the 2‐NH2group resulting in compound1. Also 2′,3′‐dideoxyisoguanosine (2) was prepared employing the photo‐substitution of the 2‐substituent of 2‐chloro‐2′,3′‐dideoxyadenosine (4). The latter was synthesized byBartondeoxygenation from 2‐chloro‐2′‐deoxyadenosine (3) orviaglycosylation of 2,6‐dichloropurine (12) with the lactol13. Compound1was less stable at the N‐glycosylic bond than 2′‐deoxyguanosine (5). The dideoxynucleoside2was deaminated by

ISSN:0018-019X    

DOI:10.1002/hlca.19940770305

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractA series of 2′‐benzamido‐2′‐deoxyadenosine analogues were synthesized in an effort to find new lead structures for the treatment of sleeping sickness. The 2′‐deoxy‐2′‐(3‐methoxybenzamido)adenosine (1h) was proved to be a selective inhibitor of the parasite glyceraldehyde 3‐phosphate dehydrogenase which confirms the modeling studies. The solution‐state conformation of 2′‐(thiophene‐2‐carboxamido) analogue1ddemonstrates a 2′‐endoconformation, an orientation of the thiophene ring under the ribose moiety, and the base part

ISSN:0018-019X    

DOI:10.1002/hlca.19940770306

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe decomposition of cyclohexyl diazoacetate (5a) in the presence of the chiral [Rh2{(2S)‐mepy}4] catalyst leads to a 3:1cis/transmixture of bicyclic lactone6awith an enantiomeric excess of 95–97% (cis) and 90% (trans). The conformationally rigidtert‐butyl derivatives5band5cafford, in the presence of the same catalyst,6band6c, respectively,viainsertion into the equatorial CH bonds exclusively, with ee's ofca.95%. A remarkable degree of induction (92–95%) results in the lactone6gupon decomposition of 1‐isopropyl‐2‐methylpropyl diazoacetate (5g). The diazoacetates derived from 1‐methylcyclohexanol, cyclopentanol and 1‐methylcyclopentanol (5d–f) afford under similar conditions insertion products with higher diastereoselectivity, but significantly lower enantioselectivity. Other dirhodium catalys

ISSN:0018-019X    

DOI:10.1002/hlca.19940770307

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe 2,4‐bis‐functionalized phenol1is dehydrogenated regioselectivity with potassium ferricyanide, affording the correspondingp‐quinonemethide2. Hydrolysis of2affords a mixture of dithioacetal5aand benzaldehyde6; 1,6‐addition of thiols to2gives the dithioacetals5of benzaldehyde6; reaction of2with 2,2′‐azobis(isobutyronitrile) (= 2,2′‐dimethyl‐2,2′‐azobis(propanenitrile)) leads to9a, 9b, and10, addition products of the 1‐cyano‐1‐methylethyl radical. The structures of all products are confirmed mainly by1H‐ and13C‐NMR spectroscopy, and the mode

ISSN:0018-019X    

DOI:10.1002/hlca.19940770308

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe first synthesis of (Z)‐neomanoalide (4) and an improved synthesis of its (E)‐isomer3was accomplished in a concise, regiocontrolled manner by exploiting 2‐[(tert‐butyl)dimethylsiloxy]‐4{[(tert‐butyl)dimethylsiloxy]‐methyl}furan (6) as the key reagent. Lithiation of6and subsequent reaction with the (2Z)‐ or (2E)‐isomer of (6E)‐3‐{[(tert‐butyl)dimethylsiloxy]methyl}‐7‐methyl‐9‐(2′,6′,6′‐trimethylcyclohex‐1′‐enyl)nona‐2,6‐dienyl bromide (5), followed by hy

ISSN:0018-019X    

DOI:10.1002/hlca.19940770309

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe conformational space of the trisaccharide α‐L‐Fuc‐(1→2)‐β‐D‐Gal‐(1→3)‐β ‐D‐GalNAc‐1‐OPr (2) and of its component disaccharide moieties α ‐L‐Fuc‐(1→2)‐β ‐D‐Gal‐1‐OMe (3) and β ‐D‐Gal‐(1→3)‐β‐D‐GalNAc‐1‐OPr (4) was investigated with the aid of molecular‐mechanics energy minimizations and molecular‐dynamics simulations. These calculations suggested the occurrence of two conformations for each compound characterized by different ϕ and Ψ glycosidic angles. However,1H‐NMR investigation of D2O solutions of2–4indicated a sure preference for one of the tw

ISSN:0018-019X    

DOI:10.1002/hlca.19940770310

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis on solid phase of a new derivative of the anticoagulant protein hirudin is described (seeSchemeandFig.1,I). The henicosapeptide is a bivalent conjugate of the C‐terminus of hirudin and of the active‐site‐binding tetrapeptideD‐Phe‐Pro‐Arg‐Pro linkedviaa tetraglycine spacer. The peptide, for which the name hirufos was coined, incorporates a stable phosphono derivative ofL‐phenylalanine which, combined with the other structural modifications, leads to a potent anticoagulant agent. Synthesis was readily achieved by the (9H‐fluoren‐9‐yl)‐methoxycarbonyl (Fmoc) strategy followed by acidolytic cleavage from the resin and deprotection, including the liberation of the crucial phosphonic

ISSN:0018-019X    

DOI:10.1002/hlca.19940770311

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY