Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. VII. Synthese von (3R)‐3‐Hydroxyretinol, (3R)‐3‐Hydroxyretinal und (3R)‐3‐Hydroxyretinsäure

Abstract

Synthesis of optically active natural carotenoids and structurally related compounds VII. Synthesis of (3R)-3-hydroxyretinol, (3R)d-hydroxyretinal and (3R)-3-hydroxyretinoic acid SummaryThe synthesis of (3R)-3-hydroxyretino1(7), (3R)-3-hydroxyretinal(9) and (3R)-3-hydroxyretinoic acid (5) according to the building principle C,, + C5 = C,, is reported utilizing the optically active C15-phosphonium salt 2 and the C,-aldehyde ester 3.

Dependency on light and vitamin A derivatives of the biogenesis of 3-hydroxyretinal and visual pigment in the compound eyes of Drosophila melanogaster.

“…The action spectrum becomes broader at higher intensities and differs from that of the photoconversion of metarhodopsin to rhodopsin, which has a peak at ~580 nm. Free all-tram hydroxyretinal in organic solvents absorbs maximally in the near-ultraviolet range, at ~385 nm (Mayer and Santer, 1980). It is, therefore, apparent that all-tram 3-hydroxyretinal in the fly retina exists neither as the chromophore of the pigment nor in the free state.…”

“…To summarize the main features of the photoisomerization, it is, firstly, highly sensitive and efficient: ~70% of the all-trans precursor can be photoisomerized by irradition of the fly with 410-430 nm light, at <1014 photons cm-~.s -~ for 1 h. Secondly, the formation of photoproduct, the 11-c/s isomer, is highly specific. Finally, the peak of the action spectrum of the photoisomerization shifts to a wavelength some 30-40 nm longer than the absorption maximum of the free all-trans 3-hydroxyretinal (386 nm in chloroform; Mayer and Santer, 1980). It is strongly suggested that the precursor, 3-hydroxyretinal, is bound to a specific binding protein, as is the case for the retinal-based pigment systems, such as the retinochrome in the cephalopod retina (Hara and Hara, 1972) or retinal-binding proteins in the honeybee retina (Pepe et al, 1976).…”

Synthetic Scheme for the Preparation of 13C‐Labeled 3,4‐Didehydro‐Retinal, 3‐Hydroxyretinal, and 4‐Hydroxyretinal up to Uniform 13C‐Enrichment

“…[16] The all-E retinals were isolated by purification of the mixture of isomers via column chromatography or HPLC, according to literature procedures. [3,11,17,18] The final products were characterized using 1 H and 13 C NMR spectroscopy; the analytical data proved to be identical to the data reported for the authentic compounds. [3,11,19,20] …”

“…Scheme 1. Synthesis of racemic 4-hydroxy-β-cyclocitral (9), safranal (10), and racemic 3-hydroxy-β-cyclocitral (11) The β-cyclocitral derivatives 9, 10, and 11 can easily be converted into the corresponding retinals 2, 3, and 4 by a HornerϪWadsworthϪEmmons (HWE) coupling with phosphonate 12 and subsequent Dibal-H reduction to obtain the intermediate β-ionylidene acetaldehydes. Repetition of the phosphonate coupling reaction and reduction gives the retinal derivatives 2, 3, and 4 as depicted in Scheme 2.…”

“…In this paper we discuss the efficient conversion of 5 into racemic 4-hydroxycyclocitral (9), safranal (10), and racemic 3-hydroxycyclocitral (11). The cyclocitral derivatives serve as C 10 -building blocks for the synthesis of the corresponding retinal derivatives 3,4-didehydroretinal (2), (R)-3-hydroxyretinal (3), and (R)-4-hydroxyretinal (4) (see Figure 1).…”