4071-74-3Relevant articles and documents
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.
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
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.