- Highly selective macrocyclic ring-closing metathesis of terminal olefins in non-chlorinated solvents at low dilution
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A set of new ruthenium-indenylidene complexes bearing two unsymmetrical unsaturated N-cycloalkyl-NHC ligands were synthesized. These catalysts proved to be highly selective in the macrocyclic ring-closing metathesis performed in non-chlorinated solvents at low dilution (0.01 M). Without the requirement of benzoquinone derivatives to prevent the isomerisation side reactions, this environmentally friendly catalytic process promoted the synthesis of macrocyclic odorant molecules with remarkable >99% purity.
- Dumas, Adrien,Colombel-Rouen, Sophie,Curbet, Idriss,Forcher, Gwénael,Tripoteau, Fabien,Caijo, Frédéric,Queval, Pierre,Rouen, Mathieu,Baslé, Olivier,Mauduit, Marc
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p. 436 - 443
(2019/01/28)
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- Fluorinated Musk Fragrances: The CF2Group as a Conformational Bias Influencing the Odour of Civetone and (R)-Muscone
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The difluoromethylene (CF2) group has a strong tendency to adopt corner over edge locations in aliphatic macrocycles. In this study, the CF2group has been introduced into musk relevant macrocyclic ketones. Nine civetone and five muscone analogues have been prepared by synthesis for structure and odour comparisons. X-ray studies indeed show that the CF2groups influence ring structure and they give some insight into the preferred ring conformations, triggering a musk odour as determined in a professional perfumery environment. The historical conformational model of Bersuker and co-workers for musk fragrance generally holds, and structures that become distorted from this consensus, by the particular placement of the CF2groups, lose their musk fragrance and become less pleasant.
- Callejo, Ricardo,Corr, Michael J.,Yang, Mingyan,Wang, Mingan,Cordes, David B.,Slawin, Alexandra M. Z.,O'Hagan, David
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supporting information
p. 8137 - 8151
(2016/06/13)
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- A novel, short and repeatable two-carbon ring expansion reaction by thermo-isomerization: Easy synthesis of macrocyclic ketones
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A novel two-carbon ring enlargement procedure, in which medium- and large-ring 1-vinylcycloalkanols are thermoisomerized in a flow reactor system at temperatures of 600°C to about 650°C, produces the isomeric ring-expanded cycloalkanones directly and efficiently. This two-step ring expansion protocol can easily be applied several times successively. For e.g., the musk odorant cyclopentadecanone (Exaltone?) is prepared from cycloundecanone in two repetitive cycles. Thermo-isomerization of the corresponding ethynylic cycloalkanols gives in moderate yields the bishomologous α,β-unsaturated macrocyclic (E)-2-cycloalkenones. A reaction mechanism via alkyl hydroxyallyl biradical intermediates is proposed.
- Nagel, Matthias,Hansen, Hans-Ju?rgen,Fra?ter, Georg
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p. 275 - 279
(2007/10/03)
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- A facile electrochemical approach for the synthesis of macrocyclic alkanones
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The synthesis of macrocyclic alkanones, viz. cyclotetradecanone 4a, cyclohexadecanone 4b, cyclooctadecanone 4c, cyclopentadecanone 4d and cycloheptadecanone 4e have been carried out by using Kolbe symmetrical/unsymmetrical dimerization followed by cyclization in Na-xylene and subsequent reduction with Zn-HCI in 70-80% yield. The products of anodic cross coupling have been separated by column chromatography over silica gel (60-120 mesh) by eluting with benzene-methanol (95: 5). An effort has been made to optimize the electrochemical step by investigating the effect of different parameters, viz. degree of partial neutralization, current density and electrode material. The products have been characterised by elemental analyses and IR and 1H NMR spectral data.
- Singh, Arpita,Singhal, Nishi,Agrawal, Hemlata,Yadav, Ashok K.
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p. 423 - 426
(2007/10/03)
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