Günter Haufe

Elucidation of the structure of an unusual cyclic glycolipid from Torulopsis apicola

Abstract The yeast Torulopsis apicola produces a microcrystalline mixture of glycolipids, the major component of which has been identified as the novel 16-(2′- O -β- d -glucopyranosyl-β- d -glucopyranosyloxy)hexadecanoic acid 1′,4″-lactone 6′,6″-diacetate ( 2 ) by spectroscopic methods.

Reactions of cyclooctene compounds with fluorinating agents

Abstract A comparative study of the reactivity of 9-oxabicyclo[6.1.0] non-4-ene compared to the corresponding aziridine shows trans- opening of the epoxide with the almost neutral fluorinating reagent (Et 3 N, 3HF) but no reaction with the aziridine. With Olahs reagent double bond participation is observed in the reaction of the epoxide while a stereoselective addition of HF to the double bond without participation of the aziridine ring takes place with 9-azabicyclo[6.1.0]non-4-ene under the same conditions.

Oxygenation of Hexadecane in the Biosynthesis of Cyclic Glycolipids in Torulopsis Apicola

Biotransformation of [1-13C] labelled hexadecane, hexadecanol and hexadecanoic acid have been investigated using the yeast Torulopsis apicola. The yeast produces a microcrystalline mixture of two glycolipids, the lipophilic moiety of which consists of ω- or (ω-l)-hydroxylated hexadecanoic acid. Biosynthesis of these glycolipids takes place via hydroxylation of hexadecane, oxidation to hexadecanoic acid and ω or (ω-l)-hydroxylation of hexadecanoic acid. Feeding the cell cultures with a mixture of hexadecane and [1-13C] labelled hexadecane derivatives one observes 13C enrichment ratios which indicate that neither of the biohydroxylation or oxidation steps are rate limiting in the formation of the glycolipids, furthermore, two different monooxygenase systems appear to be involved in hydroxylation of hexadecane and hexadecanoic acid.

Photocatalytic oxygenation of α-pinene with molecular oxygen activated by niobium and molybdenum porphyrins: Part LXX1. Photocatalytic systems

Abstract The photocatalytic oxygenation of α-pinene using tetraphenylporphinatomolybdenum and niobium complexes and molecular oxygen results in the formation of pinene epoxide and oxygenated products derived from an allylic hydrogen abstraction mechanism. The formation of radical intermediates was verified by ESR and spin-trapping experiments.

Reaktion von (Z,Z)-1,5-Cyclooctadien mit N-Bromsuccinimid in Gegenwart von Wasser oder Methanol

The action of N-bromosuccinimide (NBS) and water on (Z, Z)-1,5-cyclooctadiene (1) results in the formation ofendo,endo-2,5-dibromo-9-oxabicyclo [4.2.1]nonane (2),endo,endo-2,6-dibromo-9-oxabicyclo[3.3.1]nonane (3),trans-6-bromo-(Z)-cycloocten-5-ol (4a),endo-6-bromo-cis-bicyclo[3.3.0]octan-2-ol (5a), andtrans-5,6-dibromo-(Z)-cyclooctene (6).2 and3 are considered to be produced from intermediary4a via transanular participation of the hydroxyl group.5a is formed in a result of transanular double bond participation.The reaction of1 withNBS and methanol similarly produces2, 3,trans-6-bromo-5-methoxy-(Z)-cyclooctene (4b),endo-6-bromo-2-methoxy-cis-bicyclo-[3.3.0]octane (5b), and6.

Photocatalytic oxygenation of strained alicyclic alkenes with µ-oxo-bis[tetraphenylporphyrinatoiron(III)] and molecular oxygen

Iron(III) porphyrins are active catalysts for the photocatalytic epoxidation of strained cyclic alkenes and their methyl substituted derivatives with molecular oxygen.

Transannular oxygen participation in halofluorination reactions of 9-oxabicyclo[6.1.0]non-4-ene[1]

Abstract The transannular O-heterocyclization of 9-oxabicyclo[6.1.0]non-4-ene in halofluorination reactions using N-halosuccinimides and triethylamine tris-hydrofluoride or Olahs reagent, respectively, yields endo, endo-2-halo-6-fluoro-9-oxabicyclo[3.3.1.]nonane as the main product and endo,endo-2-halo-5-fluoro-9-oxabicyclo[4.2.1.]nonane as the minor compound by halonium assisted epoxide ring participation.

Hydroxybromierung und Methoxybromierung von (Z)-Cycloocten

In addition totrans-2-bromocyclooctanol andtrans-1,2-dibromocyclooctane,cis-4-bromocyclooctanol,cis-1,4-dibromocyclooctane,trans-1,4-dibromocyclooctane, and (Z)-5-bromocyclooctene are obtained, when (Z)-cyclooctene is treated with N-bromosuccinimide in the presence of water. Similarly the methoxybromination of (Z)-cyclooctene gives transanular products.

Reaktion von ( Z,Z )-1,5-Cyclononadien mit N-Bromsuccinimid in Gegenwart von Wasser oder Methanol

The action of N-bromosuccinimide (NBS) and water on (Z,Z)-1,5-cyclononadiene (1) results in transanular reactions to give 1β-bromo-3a α,4α,5,6,7,7a α-hexahydroindan-4-ol (2 a) and 2β,6β-dibromo-10-oxabicyclo[5.2.1]decane (3). The formation of2 a is a result of transanular double bond participation.3 is considered to be produced from intermediary (Z)-2β-bromo-5-cyclononen-1α-ol (6)via transanular participation of the hydroxyl group. The reaction of1 withNBS and methanol similarly produces 1β-bromo-4-methoxy-3aα,4α,5,6,7,7a α-hexahydroindan (2 b) and3.

Reaktionen von (E)-Cycloocten mitN-Bromsuccinimid in Gegenwart von Wasser oder Methanol

The reactions of (E)-cyclooctene withN-bromosuccinimide in the presence of water or methanol are described. Major products of the hydroxybromination aretrans-4-bromocyclooctanol as a product of intermediary transanular hydride migration, and two ring contracted bromohydrines. The methoxybromination has been found to occur similarly.