514-85-2Relevant academic research and scientific papers
Picosecond time-resolved multiplex coherent anti-Stokes Raman scattering spectroscopy by using a streak camera: Isomerization dynamics of all-trans and 9-cis retinal in the lowest excited triplet state
Tahara, Tahei,Toleutaev, Bulat N.,Hamaguchi, Hiro-o
, p. 786 - 796 (1994)
A picosecond time-resolved multiplex coherent anti-Stokes Raman scattering (CARS) measuring system using a streak camera was constructed.Picosecond uv laser pulses (50 ps) were used for the photoexcitation and nanosecond laser pulses (7 ns) were used as ω1 and ω2 for CARS probing.The multiplex CARS signals were spectrally analyzed by a spectrograph, and time-resolved and detected by a streak camera.This system enabled us two-dimensional (the time and frequency domain) detection of CARS signals with picosecond time resolution.The cis-trans photoisomerization dynamics of all-trans and 9-cis retinal was investigated.In the case of all-trans retinal, the CARS signals due to the "all-trans-like" T1 state appeared in accordance with the decay of the S1 fluorescence.In contrast, the appearance of the all-trans-like T1 signals was markedly delayed in the case of the 9-cis isomer.This indicates that there exists a T1 state having "9-cis-like" conformation in the picosecond time region.The lifetime of this 9-cis-like T1 state was obtained as 880 +/- 150 ps from the analysis of the rise of the all-trans-like T1 state.The mechanism of retinal photoisomerization is discussed on the basis of the obtained picosecond time-resolved data.It is concluded that the conformational change from the 9-cis to the all-trans form in the triplet manifold proceeds from the thermalized (not vibrationally excited) 9-cis-like T1 state.
Catalytic synthesis of 9-cis-retinoids: Mechanistic insights
Kahremany, Shirin,Kubas, Adam,Tochtrop, Gregory P.,Palczewski, Krzysztof
supporting information, p. 10581 - 10595 (2019/07/22)
The regioselective Z-isomerization of thermodynamically stable all-trans retinoids remains challenging, and ultimately limits the availability of much needed therapeutics for the treatment of human diseases. We present here a novel, straightforward approach for the catalytic Z-isomerization of retinoids using conventional heat treatment or microwave irradiation. A screen of 20 transition metal-based catalysts identified an optimal approach for the regioselective production of Z-retinoids. The most effective catalytic system was comprised of a palladium complex with labile ligands. Several mechanistic studies, including isotopic H/D exchange and state-of-the-art quantum chemical calculations using coupled cluster methods indicate that the isomerization is initiated by catalyst dimerization followed by the formation of a cyclic, six-membered chloropalladate catalyst-substrate adduct, which eventually opens to produce the desired Z-isomer. The synthetic development described here, combined with thorough mechanistic analysis of the underlying chemistry, highlights the use of readily available transition metal-based catalysts in straightforward formats for gram-scale drug synthesis.
Z -isomerization of retinoids through combination of monochromatic photoisomerization and metal catalysis
Kahremany, Shirin,Sander, Christopher Lane,Tochtrop, Gregory P.,Kubas, Adam,Palczewski, Krzysztof
supporting information, p. 8125 - 8139 (2019/09/19)
Catalytic Z-isomerization of retinoids to their thermodynamically less stable Z-isomer remains a challenge. In this report, we present a photochemical approach for the catalytic Z-isomerization of retinoids using monochromatic wavelength UV irradiation treatment. We have developed a straightforward approach for the synthesis of Z-retinoids in high yield, overcoming common obstacles normally associated with their synthesis. Calculations based on density functional theory (DFT) have allowed us to correlate the experimentally observed Z-isomer distribution of retinoids with the energies of chemically important intermediates, which include ground- and excited-state potential energy surfaces. We also demonstrate the application of the current method by synthesizing gram-scale quantities of 9-cis-retinyl acetate 9Z-a. Operational simplicity and gram-scale ability make this chemistry a very practical solution to the problem of Z-isomer retinoid synthesis.
Substrate specificity and subcellular localization of the aldehyde-Alcohol redox-Coupling reaction in carp cones
Sato, Shinya,Fukagawa, Takashi,Tachibanaki, Shuji,Yamano, Yumiko,Wada, Akimori,Kawamura, Satoru
, p. 36589 - 36597 (2014/01/17)
Our previous study suggested the presence of a novel conespecific redox reaction that generates 11-cis-retinal from 11-cisretinol in the carp retina. This reaction is unique in that 1) both 11-cis-retinol and all-trans-retinal were required to produce 11-cis-retinal; 2) together with 11-cis-retinal, all-trans-retinol was produced at a 1:1 ratio; and 3) the addition of enzyme cofactors such as NADP(H) was not necessary. This reaction is probably part of the reactions in a cone-specific retinoid cycle required for cone visual pigment regeneration with the use of 11-cis-retinol supplied from Mueller cells. In this study, using purified carp cone membrane preparations, we first confirmed that the reaction is a redox-coupling reaction between retinals and retinols. We further examined the substrate specificity, reaction mechanism, and subcellular localization of this reaction. Oxidation was specific for 11-cis-retinol and 9-cis-retinol. In contrast, reduction showed low specificity: many aldehydes, including all-trans-, 9-cis-, 11-cis-, and 13-cis-retinals and even benzaldehyde, supported the reaction. On the basis of kinetic studies of this reaction (aldehyde-alcohol redox-coupling reaction), we found that formation of a ternary complex of a retinol, an aldehyde, and a postulated enzyme seemed to be necessary, which suggested the presence of both the retinol- and aldehydebinding sites in this enzyme. A subcellular fractionation study showed that the activity is present almost exclusively in the cone inner segment. These results suggest the presence of an effective production mechanism of 11-cis-retinal in the cone inner segment to regenerate visual pigment.
Selective isomerization of retinal upon two-photon excitation
Sashima, Tokutake,Hashimoto, Hideki,Koshihara, Shin-ya
, p. 380 - 385 (2007/10/03)
The products of photo-isomerization when excited directly up to the two-photon-allowed 1Ag- excited state of alltrans and five cis isomers of retinal were determined. The composition of the isomers at the photo-stationary state was drastically changed as compared to one-photon excitation. The production of the 13-cis isomer was selectively increased, and the production of the dicis isomers was observed in the case of a direct excitation upon the 31Ag- state, although they were hard to be produced by one-photon excitation in n-hexane solution. These results clearly evidenced that there exist isomerization pathways via two-photon-allowed excited states.
Femtosecond ultraviolet-visible absorption study of all-trans→13-cis9-cis photoisomerization of retinal
Yamaguchi, Shoichi,Hamaguchi, Hiro-O
, p. 1397 - 1408 (2007/10/03)
The all-trans→13-cis9-cis photoisomerization reaction of retinal in aerated nonpolar solvents has been studied by femtosecond time-resolved ultraviolet-visible (UV-VIS) absorption spectroscopy. The excited-state absorption spectra in the wavelength region 400-800 nm indicate that there is no all-trans→13-cis9-cis isomerization reaction pathway that is complete in the electronic excited singlet manifold of S1, S2, and S3. The ground-state bleaching recovery of all-trans retinal monitored in the near UV (ultraviolet) wavelength region 310-390 nm shows that a perpendicular excited singlet state (p*) takes part in the all-trans→13-cis9-cis isomerization reaction. The lifetime of p* is about 7 ps, and the precursor of p* is most probably the S2 state. The isomerization quantum yield derived from the femtosecond UV absorption data agrees well with those determined by the HPLC analysis of the photoproduct. The temperature dependence of the isomerization quantum yield indicates the existence of a potential-energy barrier as high as (1.2±0.6)×103cm-1 on the reaction pathway from the S2 state to the p* state.
Vinyltin acetals in terpenic and nor-terpenic synthesis
Launay, Valerie,Beaudet, Isabelle,Quintard, Jean-Paul
, p. 937 - 946 (2007/10/03)
Vinyltin acetals obtained by stannylmetallation of homopropargyl acetals with Bu3SnMgMe/CuCN (E configuration) or by titanation of the corresponding alkyltin acetals (Z configuration) have been proved to be efficient storable precursors for the stereoselective synthesis of terpenoids, under mild experimental conditions.Due to the presence of a nucleophilic centre (Csp2-Sn bond) and of a protected electrophilic centre, they are also useful intermediates for an iterative synthesis of retinal and nor-retinoids. - Keywords: vinyltin; acetal; vinyllithium; monoterpenoid; retinal; nor-retinoid
Retinal isomer composition in some bacteriorhodopsin mutants under light and dark adaptation conditions
Song,Yang,El-Sayed,Lanyi
, p. 10052 - 10055 (2007/10/02)
The isomeric composition of retinal was measured in a number of bacteriorhodopsin (bR) mutants (D85N), D212N, R82A, Y185F, and D115N) under various conditions, using a rapid retinal extraction technique followed by HPLC analysis. Besides the 13-cis and the all-trans retinal isomers observed in wild type (wt) bR under physiological conditions, the 11-cis and 9-cis retinal isomers were observed in variable but minor amounts in the bR mutants. In addition, the values of the equilibrium constant at two temperatures and the enthalpy change for the all-trans to 13-cis isomerization process in the dark-adapted state of D212N, D85N, deionized blue bR, and wt bR were determined. We find that perturbation of the retinal cavity (pocket) by residue replacement changes the relative thermal stability of the different retinal isomers, allowing for thermal-and/or photoisomerization of the retinal chromophore along C9-C10 and C11-C12 bonds to moderately compete with the isomerization around the C13-C14 bond. The bR mutants expressed in Halobacterium salinarium studied in the present work showed normal 13-cis to all-trans light adaptation, in contrast with abnormal all-trans to 13-cis light adaptation observed for D212E, D212A, and D212N expressed in Escherichia coli, suggesting an influence of the purple membrane lattice and/or the lipids on the stability of the different retinal isomers within the protein.
Compositions of retinoids substituted with a dithiane ring, their use, and process for preparing the compounds
-
, (2008/06/13)
The invention relates to a stereospecific derivative of formula: STR1 in which R is hydrogen or a C 1 -C 4 thioalkyl. The invention also relates to the use of these compounds for the manufacture of stereospecific retinal or retinoic acid, as well as to a process for preparing the retinoids of formula (I). The invention finally relates to a cosmetic or pharmaceutcial composition which contains at least one compound of formula (I) in a suitable vehicle; the pharmaceutical composition according to the invention may be used for treating dermatological, rheumatic, respiratory or ophthalmological conditions.
Palladium-catalysed vinylation of tertiary allylic alcohols: A new protocol for the synthesis of isoprenoid aldehydes.
Bienayme,Yezeguelian
, p. 3389 - 3396 (2007/10/02)
Heck vinylation of tertiary allylic alcohols with iodo-acetal Ic, followed by an acid catalysed acetal hydrolysis-dehydration reaction, furnished isoprenoid aldehydes regioselectively in high yields.
