Hartmut Redlich

Radical cyclisation of hept-1-enitols☆

7-Deoxy-7-iodohept-1-enitols react intramolecularly to give 5-carba analogues of pyranoses (pseudo sugars) by the action of tributyltin hydride, which generates a radical at C-7. The configuration at the new chiral centre depends on the relative orientation of the oxygen functions in the starting material and the pattern of substitution.

Chiral building units from carbohydrates-XIII. : Identification of the absolute configuration of endo-brevicomin from dendroctonus frontalis and synthesis of both enantiomers from d-ribose

Abstract The synthesis of both enantiomers of endo -7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.l]octana ( endo -brevicomin, 12 and 12a ) starting froni D-ri-bose is described. Key interinediate is the open chain derivative 7 , a chiral building unit easily available from carbohydrates. Complexation gas chromatography showed the natural pheromone of males of the southern pine beetle, Dendroctonus frontalis Zimm. , to be (1R,5S,7S)- endo -brevicomin.

Hochselektive Additionen von 2-Lithio-1,3-dithian an die freie Carbonyl-Funktion offenkettiger partiell blockierter Kohlenhydrat-Derivate

Zusammenfassung The addition of 2-lithio-1,3-dithiane ( 1 ) to the unprotected carbonyl function of partially blocked carbohydrate derivatives is in those cases highly diastereoselective where it is possible to arrange the oxygen functions at the C-atoms 2 and 4 in such a formation that both together with the carbonyl oxygen can chelate the cation of 1 .

Regioselectivity in the free radical deoxygenation of diol thiocarbonates involving the tertiary hydroxy group of branched chained sugars

Abstract The cyclic thiocarbonates 1 to 3 react with tri(n-butyl)tin hydride under formation of the deoxygenation products 10 , 11 , 12 , and 14 . The unexpected regioselectivity of this reaction with the compounds 2 and 3 will be discussed in the following.

Synthese von β-glycosiden und β-glycosidisch verknüpften disacchariden der D-chalcose. Anwendung der entchlorierung mit tributylzinnhydrid

Abstract Starting from methyl 4,6-dichloro-4,6-dideoxy-α- D -galactopyranoside ( 1 ), D -chalcose (4,6-dideoxy-3- O -methyl- D - xcylo -hexopyranose) ( 5 ) was prepared by dechlorination with tributyltin hydride, selective benzoylation with benzoyl cyanide at O-2, methylation at O-3, and acid hydrolysis. D -Chalcose ( 5 ) was obtained as well by direct methylation of 1 with diazomethane at O-3, reduction with tin hydride, and hydrolysis. Chalcosyl bromide prepared from 5 was not very suitable for β-glycoside synthesis under Koenigs-Knorr conditions, and better results were obtained with 2- O -acetyl-4,6-dichloro-4,6-dideoxy-3- O -methyl-α- D -galactopyranosyl bromide, which gave β-glycosides with methanol, cyclohexanol, benzyl alcohol, 1,2:3,4-di- O -isopropylidene-α- D -galactopyranose, and methyl 2,3-di- O -benzyl-6-deoxy-α- D -glucopyranoside. After dechlorination with tributyltin hydride, the corresponding β-glycosides of D -chalcose were obtained in good yield.

Synthese der L-glycero-D-manno-heptose

Abstract Chain extension of 2,3:5,6-di-O-isopropylidene-D-manno-furanose 2 with 2-lithio-1,3-dithiane gives stereoselectively a derivative of D-glycero-D-galacto-heptose 3 . Conversion of the heptose 2 by reduction of the aldehydo function and oxidation of the 7-OH group yields the D-glycero-D-manno-heptose 18 .

Darstellung von (s) -2,5-dimethyl-2-isopropyl-2,3-dihydrofuran, einem der beiden enantiomeren des sexuallockstoffs des werftkäfers hylecoetus dermestoides L.

Abstract The optical pure title compound II is synthesized by conversion of the branched chain sugar methyl-2-C-acetyl-4,6-O-benzylidene-3-deoxy-α- d -ribo-hexopyranose (I) which is available from d -glucose. 2,5-Di-methyl-2-isopropyl-2,3-dihydrofuran is found for the first time as a natural product and represents a new type of insect pheromones.

Eine kurze Synthese von Serricornin, (4S,6S,7S)-4,6-Dimethyl-7-hydroxy-3-nonanon, dem Sexualpheromon des Tabakkäfers Lasioderma serricorne F., aus D-Glucose

Abstract Starting from d -glucose, a novel sequence of the syntheses leading to (3 S ,5 S ,6 S )-6-ethyl-3,5-dimethyltetrahydro-2 H -pyran-2-one ( 4 ) is described. Key steps are the hydrogenation of 3,5,6-trideoxy-1,2- O -isopropylidene-3- C -methyl-α- d - glycero -hex-3,5-dienose leading to 3,5,6-trideoxy-1,2- O -isopropylidene-3- C - methyl-β- l - lyxo -hexofuranose, and the base-catalyzed cyclisation and isomerisation of methyl (2 RS ,4 S ,5 S )-5-hydroxy-2,4-dimethylheptanoate into 4 . Compound 4 can be converted by a known procedure into serricornin.