1888-57-9Relevant academic research and scientific papers
Musk or violet? Design, synthesis and odor of seco-derivates of a musky carotol lead
Kraft, Philip,Popaj, Kasim
, p. 12211 - 12219 (2006)
By a six-step synthetic route consisting of a Li2MnCl4-catalyzed coupling of branched alkyl magnesium chlorides with isovaleryl and 3,3-dimethylbutanoyl chloride, Grignard reaction of the product with ethynyl magnesium bromide, dehydration and transformation into a Grignard reagent, subsequent reaction with acetaldehyde, (E)-selective hydrogenation of the alkynol triple bond with lithium aluminum hydride, and finally pyridinium chlorochromate oxidation, four sterically highly demanding target structures were synthesized diastereoselectively. These four molecular targets were designed as seco-structures to a musky carotol lead, and their olfactory profiles that merge violet like with musky notes to different extents, provide interesting insight into structure-odor correlation.
Axially chiral thioamides of acrylic acid: Correlated and uncorrelated internal rotations
Kuttenberger, Margit,Frieser, Markus,Hofweber, Martin,Mannschreck, Albrecht
, p. 3629 - 3645 (2007/10/03)
In acrylic thioamides (Scheme 1), two intramolecular motions are possible: thiocarbonyl-nitrogen (=C-N) and alkenyl-carbonyl (=C-C=) rotations. Since the two mobile molecular fragments can interact by steric and by resonance effects, we intended to demons
The reduction of α-silyloxy ketones using phenyldimethylsilyllithium
Fleming, Ian,Roberts, Richard S.,Smith, Stephen C.
, p. 1215 - 1228 (2007/10/03)
Phenyldimethylsilyllithium reacts with acyloin silyl ethers RCH(OSiMe3)COR 8 to give regiodefined silyl enol ethers RCH=C(OSiMe2Ph)R 9, and hence by hydrolysis ketones RCH2COR 10. The yields can be high but are usually moderate. The mechanism of this reduction is established to involve a Brook rearrangement (Scheme 6) rather than a Peterson elimination (Scheme 1). Although the mechanism appears to be the same in each case, the stereochemistries of the silyl enol ethers 9 are opposite in sense in the aromatic series (R = Ph, Scheme 7) and the aliphatic series (R = cyclohexyl, Scheme 8), with the major aromatic silyl enol ether being the thermodynamically less stable isomer E-PhCH=C(OSiMe2Ph)Ph E-9aa, and the major aliphatic silyl enol ether being the thermodynamically more stable isomer Z-c-C6H11CH= C(OSiMe2Ph)-c-C6H11 Z-9ba. This is a consequence of anomalous anti-Felkin attack in the aromatic series. The reaction with the silyl ether ButCH(OSiMe3)COPh 13b is normal in giving Z-ButCH= C(OSiMe2Ph)Ph Z-38 (Scheme 11), but reduction of the silyl ether 8a with lithium aluminium hydride is also anti-Felkin giving with high selectivity the meso diol PhCH(OH)CH(OH)Ph 39. The reaction between Phenyldimethylsilyllithium and the acyloin silyl ether 8d (R = But) does not give the ketone ButCH2COBut, but gives instead the anti-Felkin meso diol ButCHOHCHOHBut 40 also with high selectivity (Scheme 12). Silyllithium and some related reagents react with trifluoromethyl ketones 46 and 48 to give α,α-difluoro silyl enol ethers 47 and 49 (Scheme 14).
Zinc-promoted reactions. Part 5. The behaviour of alkyl substituted 1,3-diketones
Floris, Barbara,Luchetti, Luciana,Rosnati, Vittorio
, p. 4409 - 4418 (2007/10/02)
The zinc-promoted reaction of 2,4-pentanedione and related β-dicarbonyl substrates have been investigated under a variety of conditions. The results were explained according to a general mechanism, involving ionic and nonionic pathways.
Photochemistry in solution-XX. Triplet reactivity of aliphatic aldehydes
Kossanyi,Sabbah,Chaquin,Ronfart-Haret
, p. 3307 - 3315 (2007/10/02)
The triplet self-quenching process of three aliphatic aldehydes has been investigated by inhibition with dienes (taking into account the singlet interaction with the dienes) and by laser flash photolysis. The results obtained for intersystem crossing, the setf-quenching process and product formation have been rationalized. The main reactivity observed for the three aldehydes is the self-quenching process which occurs from both the singlet and triplet state. The laser flash photolysis experiments carried out with butanal show two absorptions of a transient at 320 aod 355 nm; no evidence for two different species could be put forward. The similar decay of the two absorption maximas of the transient, as the concentration of aldehyde is increased, would be indicative of only one single absorbing species which could be either the triplet state of the aldehyde or a radical-pair formed by the self-quenching process or the 1,4-biradical resulting from γ-H abstraction. The fact that both the quenching experiments (by dienes or by 1-methylnaphthalene) and the laser flash measurements lead to about the same lifetime also indicates only one species. The products formed from the triplet setf-quenching process have also been obtained by a different method: excitation of benzophenone at 365 nm in the presence of butanal. The quantum yields for product formation is about the same as those obtained for the triplet by direct irradiation of butanal, except that of octane-4,5-dione which is increased if the photoreaction is carried out at 365 nm in the presence of beazophenone.
