Helvetica Chimica Acta

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Total Synthesis of Indole and Dihydroindole Alkaloids. XV. Further Chemistry of Vindoline
Helvetica Chimica Acta - Tập 61 Số 5 - Trang 1554-1564 - 1978
James P. Kutney, Ursula Bünzli-Trepp, Toshio Honda, Junki Katsube, Brian R. Worth
AbstractThe general reactivity of various sites in the vindoline series has been investigated. The facility of electrophilic substitution at C(15) and the effect of steric crowding on reactions at C(4) are discussed. At the basic nitrogen sites, oxidations with mercuric acetate and potassium permanganate are also discussed.
Microbial Transformation of Sesquiterpenes, (−)‐Ambrox® and (+)‐Sclareolide
Helvetica Chimica Acta - Tập 87 Số 10 - Trang 2685-2694 - 2004
M. Iqbal Choudhary, Syed Ghulam Musharraf, Amtul Jamil Sami, Atta‐ur Rahman
AbstractThe microbial transformation of (−)‐Ambrox® (1), a perfumery sesquiterpene, by a number of fungi, by means of standard two‐stage‐fermentation technique, afforded ambrox‐1α‐ol (2), ambrox‐1α,11α‐diol (3), ambrox‐1α,6α‐diol (4), ambrox‐1α,6α,11α‐triol (5), ambrox‐3‐one (6), ambrox‐3β‐ol (7), ambrox‐3β,6β‐diol (8), 13,14,15,16‐tetranorlabdane‐3,8,12‐triol (9), and sclareolide (10) (Schemes 1 ... hiện toàn bộ
Untersuchungen in der Benztropylium‐Reihe XII. Absorptionsspektrum und Acidität benzologer Tropylium‐Kationen
Helvetica Chimica Acta - Tập 43 Số 5 - Trang 1221-1243 - 1960
G. Naville, Hansruedi Strauss, E. Heilbronner
AbstractThe series of benzologue tropylium cations up to C15 has been completed by the preparation of 1,2; 3,4‐dibenzo‐tropylium cation (III), of (1′,2′‐naphtha)‐tropylium cation (V) and of (2′,3′‐naphtha)‐tropylium cation (IV). The absorption spectra and the relative acidities of these compounds are described.
Desorption/Chemical Ionization Mass Spectrometry of Naturally Occurring Glycosides
Helvetica Chimica Acta - Tập 64 Số 1 - Trang 297-303 - 1981
Kurt Hostettmann, J. Doumas, Michel Hardy
AbstractDesorption/chemical ionization mass spectrometry (D/CI.‐MS.) is a recently developed technique especially indicated for highly polar and non volatile compounds. Various naturally occurring glycosides such as saponins, iridoid and secoiridoid glycosides, cardenolides and flavone‐O‐glycosides have been investigated by this method. All the measurements were carried out on underivatized compou... hiện toàn bộ
Synthesis of 2‐Acetamido‐2‐deoxy‐D‐gluconhydroximolactone‐ and Chitobionhydroximolactone‐Derived N‐Phenylcarbamates, Potential Inhibitors of β‐N‐Acetylglucosaminidase
Helvetica Chimica Acta - Tập 73 Số 7 - Trang 1918-1922 - 1990
Dieter Beer, Jean‐Luc Maloisel, Dora M. Rast, Andrea Vasella
AbstractThe N‐phenylcarbamate 7, derived from 2‐acetamido‐2‐deoxy‐D‐gluconhydroximo‐1,5‐lactone (3) and the analogous N‐phenylcarbamate 14, derived from chitobionhydroximo‐1,5‐lactone (10) have been prepared as potential inhibitors of β‐N‐acetylglucosaminidases. The unambiguous synthesis of the hydroximo‐1,5‐lactone 3 involves oxidation of the oxime 1, followed by deprotection with Na/NH3.
Synthesis of 5‐(Arylselanyl)‐2‐(arylsulfanyl)benzoates by [3+3] Cyclocondensation of 3‐(Arylsulfanyl)‐1‐(silyloxy)buta‐1,3‐dienes with 2‐(Arylselanyl)‐3‐(silyloxy)alk‐2‐en‐1‐ones
Helvetica Chimica Acta - Tập 93 Số 9 - Trang 1779-1784 - 2010
Inam Iqbal, Muhammad Imran, Peter Langer
AbstractFunctionalized 5‐(arylselanyl)‐2‐(arylsulfanyl)benzoates were prepared by [3+3] cyclocondensation of 3‐(arylsulfanyl)‐1‐(silyloxy)buta‐1,3‐dienes with 2‐(arylselanyl)‐3‐(silyloxy)‐alk‐2‐en‐1‐ones.
Linear‐Reactor‐IR.‐Matrix and Microwave Spectroscopy of the System O3/NO2/(Z)‐2‐Butene
Helvetica Chimica Acta - Tập 65 Số 2 - Trang 504-520 - 1982
J. Dommen, Martin Förster, Heidi Ruprecht, A. Bauder, Hans‐Heinrich Günthard
AbstractInvestigation of the formation of complex reaction products in the gas‐phase system O3/NO2/(Z)‐2‐butene by combination of linear reactors with IR. matrix and microwave Stark Spectroscopy is reported. Besides the polyatomic products observed earlier in the gas‐phase ozonolysis of (Z)‐2‐butene, the following products were identified; N2O5, HNO3, HNO4, CH3NO2, CH3ONO, CH3COONO2 and CH3COO2NO2... hiện toàn bộ
Novel Naamidine‐Type Alkaloids and Mixed‐Ligand Zinc(II) Complexes from a Calcareous Sponge, Leucetta sp., of the Coral Sea
Helvetica Chimica Acta - Tập 78 Số 5 - Trang 1178-1184 - 1995
Ines Mancini, Graziano Guella, Cécile Debitus, Francesco Pietra
AbstractAs compounds from a calcareous sponge, Leucetta sp., of the Coral Sea, we isolated a series of novel naamidine‐type alkaloids, 6–10, which are oxidized at a single benzylic position. We also report on the first marine, mixed‐ligand metal complex 5 and on the first natural metal complexes 3 and 4 derived from classical naamidines, i.e., 1 and 2. The latter are also present in free form in t... hiện toàn bộ
Über den Mechanismus der enzymatischen Verseifung von Pektinstoffen
Helvetica Chimica Acta - Tập 38 Số 1 - Trang 321-329 - 1955
J. Solms, H. Deuel
AbstractEs wird die Kinetik der enzymatischen Verseifung von verschiedenen Pektinstoffen durch Orangenpektinesterase untersucht. Die enzymatische Verseifung erfolgt stets unvollständig bis zu einem Veresterungsgrad von ca. 10%.
Über Toxine II. Zur Kenntnis des Crotins
Helvetica Chimica Acta - Tập 8 Số 1 - Trang 384-392 - 1925
P. Karrer, Fritz Gerd Weber, J. van Slooten
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