72008-46-9Relevant academic research and scientific papers
Amberlyst-15-catalyzed intramolecular S(N)2' oxaspirocyclization of secondary allylic alcohols. Application to the total synthesis of spirocyclic ethers theaspirane and theaspirone
Young, Jenn-Jong,Jung, Liarng-Jyur,Cheng, Kuang-Ming
, p. 3415 - 3418 (2007/10/03)
A variety of substituted 1-oxaspiro[4.4]non-6-ene. 1-oxaspiro[4.5]dec-6- ene, 6-oxaspiro[4.5]dec-1-ene and 1-oxaspiro[5.5]undec-7-ene systems have been prepared by utilizing Amberlyst-15-catalyzed intramolecular S(N)2' oxaspirocyclizations of secondary allylic alcohols under mild reaction conditions in quantitative yields. This oxaspirocyclization was applied to the total synthesis of theaspirane and theaspirone from β-ionone in five steps. (C) 2000 Elsevier Science Ltd.
Novel allylic oxidation of conjugate ketones with VO(OR)Cl2
Hirao,Mikami,Mori,Ohshiro
, p. 1741 - 1744 (2007/10/02)
An oxo group is introduced at the allylic position of 3-methyl-2-cyclopenten-1-one and β-ionone on treatment with VO(OR)Cl2 in ROH. VO(OR)Cl2 induces γ-alkoxylation in the case of 2-cyclopenten-1-one. Reaction of 1-acetyl-1-cyclohexene with VO(OEt)Cl2 results in γ-alkoxylation and/or aromatization to give 1-acetyl-3-ethoxy-1-cyclohexene and the corresponding aromatic.
Structure-Odor Correlation, VII. - Synthesis and Olfactive Properties of Theaspirane Analogues
Weyerstahl, Peter,Buchmann, Bernd,Marschall-Weyerstahl, Helga
, p. 507 - 524 (2007/10/02)
The spirodihydrofurans 8-12 were prepared by addition of the respective alkynols to the ketone 20 (-->21-25), Lindlar hydrogenation (-->26-30), and cyclization. - The saturated derivatives 1-6 were available either by hydrogenation (8-10-->1,2,4) or via the lactol 47 and its reaction to the diols 31-36.Addition of the ethyl acetate anion to 20 (-->71), reduction (71-->73), and cyclization yielded the spirooxetane 13. - From the ynediols 76 and 77, Lindlar hydrogenation (-->78,79), cyclization (-->80,81), and further hydrogenation led to the spirotetrahydropyranes 16and 17. - Key compound for the synthesis of the ketone 18 was the geranic acid derivative 94, which could be obtained in two different ways.Cyclization of 94 to the diester 92 and Dieckmann condensation of 92 under simultaneous methylation (-->99) led to 18.The diastereoisomers 18a and b could be assigned after reduction of 18 to the separable alcohols 19a-c. - The olfactive properties (strength and quality) of the theaspirane analogues are determined by the conformational flexibility of the respective molecule.Thus, the almost rigid 13 has a very strong camphoraceous-herbaceous odor.Augmenting flexibility, particularly by increasing of the ring size (-->1,-->16), but also by alkyl substitution at C-2, results in remarkably weaker, woody-flowery notes.
Photochemical Reactions 149. Photochemistry of 7,8-Dihydro-4-hydroxy-β-Ionone and Derivatives
Pascual, Alfons,Bischofberger, Norbert,Frei, Bruno,Jeger, Oskar
, p. 374 - 388 (2007/10/02)
The photolysis of 7,8-dihydro-4-hydroxy-β-ionone (6) was investigated together with its acetate and isopropyl ether 7 and 8, respectively.Irradiation (λ > 245 nm) of 6 in MeCN or i-PrOH at temperatures between 25 deg and -65 deg leads to the tricyclic eth
A SYNTHETIC APPROACH TO TAXANE DITERPENES. A SYNTHESIS OF THE BICYCLOUNDECENONE RING SYSTEM
Ohtsuka, Yasuo,Oishi, Takeshi
, p. 203 - 206 (2007/10/02)
Bicycloundecenone 2 corresponding to A and B rings in taxane diterpenes was synthesized.The eight-membered ring was constructed by a base-induced intramolecular cyclization of twelwe-membered lactam sulfoxides 15.
