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Schulte‐Elte, K. H.; Willhalm, B.; Thomas, A. F.; Stoll, M.; Ohloff, G.
doi: 10.1002/hlca.19710540703pmid: N/A
The photolysis of cyclic ketones from C9 to C16 has been carried out, and formation of cyclobutanols observed in only C11 to C16. Although in the mass spectrometer cyclobutanols are not formed, an initial transfer of a γ‐hydrogen atom to the carbonyl group is shown to occur in the mass spectra of all cyclic ketones higher than C10.
doi: 10.1002/hlca.19710540704pmid: N/A
The odor principle β‐damascenone and its isomer α‐damascenone have been prepared by treatment of the corresponding ethyl safranates with excess allyl lithium followed by alkoxide catalyzed isomerization of the resulting products with β, γ‐unsaturated ketonic side chains. Addition of allyltriphenylphosphorane (preferably prepared from allyltriphenylphosphonium chloride) rather than the propenyl isomer to ethyl α‐isopropylidene‐acetoacetate produced ethyl α‐safranate. This represents a new, potentially general method for the synthesis of functionalized cyclohexadienes.
doi: 10.1002/hlca.19710540705pmid: N/A
The 6 R configuration of (+)‐cis‐γ‐irone [(+)‐4] was established by chemical correlation with (—)‐camphor. (+)‐cis‐γ‐irone [(+)‐4] was converted into (+)‐cis‐α‐irone [(+)‐1], (−)‐trans‐α‐irone [(minus;;)‐2], and (+)‐β‐irone [(+)‐3], which therefore also have the 6 R configuration. The 2 S configurations of (+)‐cis‐α‐irone [(+)‐1] and (+)‐trans‐α‐irone [(+)‐2] were determined by comparison of their circular dichroism with that of R‐α‐ionone [(+)‐5]. The 2 S configuration of (+)‐cis‐γ‐irone [(+)‐4] was established by chemical correlation with (+)‐cis‐α‐irone [(+)‐1].
doi: 10.1002/hlca.19710540706pmid: N/A
The sodium salts of the tricyclic tosylhydrazones 1, 4 and 5 yield by base‐catalyzed fragmentation between 130–160° the monocyclic ring expansion products 2, 3 and 6. IR.‐spectrometry suggests a diazoalkane A as the principal intermediate of the fragmentation. Besides the known carbene mechanism the reaction is considered to pass through a noncarbenoid intermediate.
Skorianetz, W.; Giger, H.; Ohloff, G.
doi: 10.1002/hlca.19710540707pmid: N/A
The enantiomers of 7‐hydroxy‐dihydrocitronellal have been prepared stereo‐specifically from (+)‐pulegone by a sequence of analogous reactions. The olfactory properties of the final products and of the intermediates have been investigated. In most cases they exhibit remarkable qualitative and quantitative differences in odour.
Sundt, E.; Willhalm, B.; Chappaz, R.; Ohloff, G.
doi: 10.1002/hlca.19710540708pmid: N/A
The diastereoisomeres of p‐menthone‐8‐thiol, derived from (+)‐menthol, are the first ketothiols of the terpene series to have been found in nature. Stereochemistry, methods of preparation and olfactory properties of the new compounds are described.
Schulte‐Elte, K. H.; Rautenstrauch, V.; Ohloff, G.
doi: 10.1002/hlca.19710540709pmid: N/A
Under the conditions of the Wharton reaction, the (±)‐epoxy‐γ‐dihydroionones 2 and 3 are transformed into the allylic alcohols 4–10. γ‐Damascols 4, 5 and 8 were oxidised to cis‐ and trans‐γ‐damascone 12 and 13. Alternatively, dehydro‐γ‐damascol 18 was obtained by Wittig rearrangement of butinyl ether 17, and converted into damascones 12 and 13.
Schulte‐Elte, K. H.; Gadola, M.; Ohloff, G.
doi: 10.1002/hlca.19710540710pmid: N/A
Short‐path thermolysis of (+)‐isopinocampheol (1) at about 330° in the gas phase yields mainly (—)‐(3 S, 4 S)‐3, 7‐dimethyl‐octa‐1,6‐dien‐4‐ol (2). Longer heating of 2 at about 290–330° yields as main products the diastereoisomeric hydroxy‐Δ8‐iridenes 3, 4 and 5 in ratios dependent on temperature. Above 400°, formation of 4‐methylpent‐3‐en‐1‐al (7) and 2‐butene (8) predominates. Compounds 7 and 8 also appear as the stable final thermolysis products of 3, 4 and 5 above 500°. Small quantities of (+)‐iso‐dihydrocarveol (6) always occur as by‐product in the thermolysis of 1.
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