Both C=C-bond isomers of cyclohexadec-7-enone (6, Aurelione(®) ) were selectively synthesized via cyclohexadec-7-ynol (16) by ring-closing alkyne metathesis of icosa-2,18-diyn-9-ol (15), employing an in situ-formed catalyst from Mo(CO)6 and 4-(trifluoromethyl)phenol. Pyridinium chlorochromate (PCC) oxidation and subsequent Lindlar hydrogenation afforded the (7Z)-configured isomer (7Z)-6, while hydrosilylation of the intermediate cyclohexadec-7-ynone (17), followed by desilylation, provided the (7E)-configured cyclohexadec-7-enone ((7E)-6). The substrate for the alkyne metathesis was prepared from cycloheptanone (7) by cycloaddition of chloromethylcarbene to its trimethylsilyl enol ether 8, and subsequent ring enlargement of the adduct 9 under rearrangement to 2-methylcyclooct-2-enone (10), which was subjected to Weitz-Scheffer epoxidation and Eschenmoser-Ohloff fragmentation to non-7-ynal (12). Its reaction with the Grignard reagent of 11-bromoundec-2-yne (14), prepared from the corresponding alcohol 13 by Appel-Lee bromination, furnished the icosa-2,18-diyn-9-ol (15). While both isomers of cyclohexadec-7-enone (6) possess warm and powdery musk odors with tobacco-type ambery accents, (7Z)-6 is more animalic and waxy, whereas (7E)-6 was found to be more floral, sweet, and hay-like in tonality. Interestingly, however, with odor detection thresholds of 2.0 ng/l air and 2.3 ng/l air, respectively, both (7Z)-6 and (7E)-6 were found to be almost identical in their odor strength, with the (7Z)-6 being only very slightly more powerful.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/cbdv.201400011 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Rh(II)-Catalyzed Selective C(sp)-H/C(sp)-H Bonds Cascade Insertion to Construct [6-8-6] Benzo-Fused Scaffold.
Org Lett
December 2024
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China.
The fused eight-membered carbocycles (EMCs) play vital roles in the medicinal and biological investigations of many natural products and marketed drugs. The traditional synthesis of [6-8-6] benzo-fused derivatives involves multistep reactions and low yields, making the development of a one-step synthesis method a more challenging work. Here, we present a novel strategy for one-step construction of [6-8-6] benzo-fused scaffold from propargyl diazoacetates substituted with benzyl-nitrogen heterocyclic ring via Rh(ll)-catalyzed carbene/alkyne metathesis (CAM) and selective C-H bond insertion.
View Article and Find Full Text PDFDensity Functional Theory Rationalization of the Mechanism, Selectivity, and Role of Substituents in Au(I)-Catalyzed Synthesis of Pyrazolines and Dihydropyridines.
J Org Chem
December 2024
College of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an 710021, P. R. China.
Article Synopsis
- - A study investigated how gold catalysts affect the synthesis of pyrazolines and dihydropyridines from imines and methyl phenylpropiolate, focusing on three different imines with unique substituents.
- - The research found that the type of nitrogen substituent influences the reaction path: NHCOMe leads to outward ring opening and pyrazoline products, while aromatic substituents prompt inward ring opening and dihydropyridine products.
- - The configuration of dihydropyridine is determined by the substituent on the aromatic ring, with electron-donating groups causing direct formation of 1,4-dihydropyridine and electron-withdrawing groups leading to 1,2-dihyd
Stabilisation of a Strontium Hydride with a Monodentate Carbazolyl Ligand and its Reactivity.
Angew Chem Int Ed Engl
November 2024
Karlsruhe Institute of Technology (KIT), Institute of Inorganic Chemistry (AOC), Engesserstr. 15, Geb. 30.45, Karlsruhe, Germany.
The molecular strontium hydride 2 [(Cbz)SrH(L)] (L=benzene, toluene) was isolated and stabilized by employing a sterically demanding carbazole ligand (Cbz=1,8-bis(3,5-ditertbutylphenyl)-3,6-ditertbutylcarbazolyl). Compound 2 was synthesized via phenylsilane metathesis with the corresponding amide (Cbz)SrN(SiMe) and characterized by H NMR, XRD and vibrational spectroscopy methods. We further investigated the stoichiometric reactivity of 2 towards carbon monoxide, azobenzene and trimethylsilylacetylene, showing three distinct reactivity pathways: addition, reduction and deprotonation.
View Article and Find Full Text PDFSynthesis of Multisubstituted Cyclopentadiene Derivatives from 3,3-Disubstituted Cyclopropenes and Internal Alkynes Catalyzed by Low-Valent Niobium Complexes.
J Am Chem Soc
December 2024
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
A low-valent niobium species generated from NbCl and 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (-Me-CHD) in combination with PPh catalyzed a [2+2+1]-cycloaddition reaction of 3,3-disubstituted cyclopropenes and 2 equiv of diaryl/dialkylalkynes, leading to isomeric mixtures of multisubstituted cyclopentadienes -. The initial catalyst activation process was a one-electron reduction of NbCl with -Me-CHD to provide [NbCl(μ-Cl) (L)] (L = PMePh (), L = PPh ()) in the presence of phosphine ligands. An NMR spectroscopic time course experiment using complex as the catalyst revealed an induction period for the product formation, corresponding to an additional one-electron reduction of by the substrates to give catalytically active η-alkyne complexes of NbCl.
View Article and Find Full Text PDFTransition metal-catalyzed alkyne metathesis has become a useful tool in synthetic chemistry. Well-defined alkyne metathesis catalysts comprise alkylidyne complexes of tungsten, molybdenum and rhenium. Non-d Re(v) alkylidyne catalysts exhibit advantages such as remarkable tolerance to air and moisture as well as excellent functional group compatibility.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!