4071-74-3Relevant academic research and scientific papers
Lipase-catalyzed Asymmetric Synthesis of Enantiomerically Pure (2S,4aS,8S)-4a,8-Dimethyl-2,3,4,4a,5,6,7,8-octahydro-2-naphthalenol
Tanaka, Akira,Tokuyama, Takahito,Saito, Akiko,Oritani, Takayuki
, p. 2435 - 2437 (2007/10/03)
Enantiomerically pure (2S,4aS,8S)-(+)-4a,8-dimethyl-2,3,4,4a,5,6,7,8-octahydro-2-naphthalenol (3), a key intermediate in the synthesis of natural geosmin (1), was prepared by enzymatic kinetic resolution. When racemic 3 was submitted to lipase (PS-30)-cataIyzed asymmetric acetylation, employing vinyl acetate as the acyl donor, requisite product (+)-3 with a high enantiomeric excess was attained as the remaining alcohol. Recrystallization resulted in an enantiomerically pure sample. - Keywords: lipase; kinetic resolution; asymmetric acetylation; geosmin; musty odour component.
A Total Synthesis of the Sesquiterpene Quinone Metachromin-A
Almeida, Wanda P.,Correia, Carlos Roque D.
, p. 1367 - 1370 (2007/10/02)
The first total synthesis of the marine natural product metachromin A was accomplished through a convergent synthesis amenable to the preparation of synthetic analogues.The main features of this synthesis are the introduction the oxygenation at C17 employing a Thiele acetoxylation reaction and a stereoselective Horner-Wadsworth-Emmons coupling of a nonstabilized phosphonate with a methyl ketone derivative to generate the required (E)-trisubstituted double bond.
Organotin Triflate as Practical Catalyst for Michael Addition of Enol Silyl Ethers
Sato, Tsuneo,Wakahara, Yoshiyuki,Otera, Junzo,Nozaki, Hitosi
, p. 9773 - 9782 (2007/10/02)
Dibutyltin bis(triflate) is a mild Lewis acid which catalyzes clean Michael addition of enol silyl ethers.The new catalyst allows to employ various labile acceptors such as methyl vinyl ketone and 2-cyclopentenone which do not undergo smooth reaction with
Organotin triflates as functional Lewis acids. A new entry to simple and efficient Robinson annulation
Sato, Tsuneo,Wakahara, Yoshiyuki,Otera, Junzo,Nozaki, Hitosi
, p. 1581 - 1584 (2007/10/02)
An efficient Robinson annulation has been established through the Michael addition of enol silyl ethers to α-enones catalyzed by dibutyltinbis(triflate) followed by the MeONa-mediated intramolecular aldol condensation of the adducts.
8,16- And 8,18-methanobacteriorhodopsin. Synthesis and spectroscopy of 8,16- and 8,18-methanoretinal and their interaction with bacterioopsin
Steen, R. van der,Biesheuvel, P. L.,Erkelens, C.,Mathies, R. A.,Lugtenburg, J.
, p. 83 - 93 (2007/10/02)
8,16- And 8,18-methanoretinal with a locked 6-s-trans and a 6-s-cis conformation have been synthesized and characterized.Their 9-Z and 13-Z isomers could also be prepared, in contrast to the 11-Z. 8,16-Methanoretinal easily binds with bacterioopsin (bO) to form a bacteriorhodopsin analogue which closely resembles natural bacteriorhodopsin (bR) (λmax, light-dark adaptation and proton pump action).The interaction of 8,18-methanoretinal with bO is complex.These findings give additional support to the fact that in bR the chromophore occurs in the planar 6-s-trans conformation.Approximately 1200 cm-1 of the opsin shift in bR (5100 cm-1) arises because the chromophore changes upon binding to the protein from a 40 deg twisted 6-s-cis to a planar 6-s-trans conformation.Both 8,16- and 8,18-methano bR have a ca. 3900 cm-1 opsin shift, since the C6-C7 conformation does not allow protein-induced changes.This is consistent with the idea that the opsin shift is mainly due to the perturbation of the Schiff base region.
1,5-DICARBONYL COMPOUNDS A GENERAL PREPARATION METHOD
Duhamel, P.,Hennequin, L.,Poirier, J. M.,Tavel, G.,Vottero, C.
, p. 4777 - 4786 (2007/10/02)
In this report, a general method for the preparation of 1,5-dicarbonyl compounds and six membered ring annelation is described.This method involves the reaction of hemiacetal vinylogs 1 with enol ethers 2 or 3 in the presence of a Lewis acid.This reaction was successfully applied to the enol ethers of α and α,α'-hindered ketones such as 2,2,6-trimethyl cyclohexanone. α-Cyperone and 6-epi-α-cyperone were obtained using this process.
UNE METHODE SIMPLE ET EFFICACE DE PREPARATION DE COMPOSES DICARBONYLES-1,5
Duhamel, Pierre,Hennequin, Laurent,Poirier, Nelly,Poirier, Jean-Marie
, p. 6201 - 6204 (2007/10/02)
We describe a convenient preparation method of 1,5-dicarbonyl compounds from enol ethers, methyl vinyl ketone and boron trifluoride etherate.In the presebce of an alcohol, high or quantitative yields are obtained even with enol ethers of hindered ketones.
NOUVELLE METHODE D'ANNELATION PAR L' INTERMEDIAIRE DE DICETONES-1,5
Duhamel, Pierre,Poirier, Jean-Marie,Tavel, Gilbert
, p. 43 - 46 (2007/10/02)
A new method for six-membered ring annelation is described which involved reaction of hemiacetal vinylogs 1 with silyl enol ethers 2 in the presence of a Lewis acid.
