Stereochemistry of Formation of theβ-Ring of Lycopene: Biosynthesis of (1R,1′R)-β,β-[16,16,16,16′,16′,16′-2H6]Carotene from [16,16,16,16′,16′,16′-2H6]Lycopene inFlavobacterium R 1560
Abstract:Dedicated to Prof. Albert Eschenmoser on the occasion of his 75th birthday Incubation of deuteriated precursors in cultures of Flavobacterium produced specifically deuteriated carotenoids. Analysis of these led to several conclusions: i) Lycopene is a direct precursor of b,b-carotene. ii) Its terminal Me groups retain their integrity during cyclization: there is a stereospecific folding of the 1,5-diene. The Me(16,16') groups of lycopene become the Me(16,16') of b,b-carotene. Consequently, the folding must fol… Show more
“…Subsequent elimination of H−x + affords the double bond between C-5 and C-6 and the correct stereochemical arrangement of the two biogenetically nonequivalent methyl groups at C-1. The results are in line with the stereochemical course of ring formation in certain plants and bacteria. ,, 7 Stereochemical course of ring formation during the biosynthesis of zeaxanthin in Paracoccus sp. strain PTA-3335.…”
Section: Resultssupporting
confidence: 80%
“…The results are in line with the stereochemical course of ring formation in certain plants and bacteria. 28,30,31 Experimental Section Materials. Unlabeled D-glucose monohydrate was purchased from Fluka (Milwaukee, WI).…”
Cultures of the zeaxanthin-producing bacterium Paracoccus species strain PTA-3335 (formerly Flavobacterium) were grown with supplements of (13)C-labeled glucose. Zeaxanthin was isolated and analyzed by (13)C NMR spectroscopy. The data showed that the isoprenoid precursors of zeaxanthin were biosynthesized via the mevalonate pathway. The microorganism was found to utilize glucose mainly via the Entner-Doudoroff pathway.
“…Subsequent elimination of H−x + affords the double bond between C-5 and C-6 and the correct stereochemical arrangement of the two biogenetically nonequivalent methyl groups at C-1. The results are in line with the stereochemical course of ring formation in certain plants and bacteria. ,, 7 Stereochemical course of ring formation during the biosynthesis of zeaxanthin in Paracoccus sp. strain PTA-3335.…”
Section: Resultssupporting
confidence: 80%
“…The results are in line with the stereochemical course of ring formation in certain plants and bacteria. 28,30,31 Experimental Section Materials. Unlabeled D-glucose monohydrate was purchased from Fluka (Milwaukee, WI).…”
Cultures of the zeaxanthin-producing bacterium Paracoccus species strain PTA-3335 (formerly Flavobacterium) were grown with supplements of (13)C-labeled glucose. Zeaxanthin was isolated and analyzed by (13)C NMR spectroscopy. The data showed that the isoprenoid precursors of zeaxanthin were biosynthesized via the mevalonate pathway. The microorganism was found to utilize glucose mainly via the Entner-Doudoroff pathway.
“…Syntheses of ( E )-[4- 2 H 3 ]3-methyl-2-butenyl diphosphate ( ( E )-[4,4,4- 2 H 3 ]1-OPP ) and ( Z )-[4- 2 H 3 ]3-methyl-2-butenyl diphosphate (( Z )-[4,4,4- 2 H 3 ]1-OPP ) are shown in Scheme . Although both compounds have been prepared previously, , the route we report is an efficient divergent synthesis that yields both stereoisomers. Benzenethiol was added to acetylenic ester 7 to give a 95% yield of a ∼3:1 mixture of ( E )- and ( Z )-8 , which were readily separated by column chromatography.…”
Short practical syntheses for five deuterium labeled derivatives of dimethylallyl diphosphate (DMAPP) useful for enzymological studies are reported. These include the preparation of the C1-labeled derivatives (R) Isoprenoid compounds constitute a large diverse class of "small molecule" natural products with over 35,000 individual known metabolites. The vast majority of these compounds are ultimately derived from two fundamental isoprenoid building blocks, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP, 1-OPP). DMAPP is the electrophilic primer required to initiate the 1'-4 (head-to-tail) chain elongation reactions for the biosynthesis of polyisoprenoid compounds, 1 which are generated by successive alkylations of IPP by a growing allylic diphosphate chain. 2,3 DMAPP is also the substrate for biosynthesis of monoterpenes with non-head-to-tail skeletons 4 and a variety of metabolites where the dimethylallyl moiety is attached to non-isoprenoid fragments. 1-The prenyltransfer enzymes that catalyze electrophilic alkylation reactions with DMAPP are typically highly stereoselective. Because many enzymes do not tolerate substitutions that substantially increase their steric bulk of the substrates, the stereochemistries of these reactions are best studied with isotopically labeled derivatives of the normal substrates. We now report short practical routes for the stereoselective synthesis of deuterated derivatives of DMAPP, which collectively place label at each of the carbons bearing hydrogen atoms. Publisher's Disclaimer: This PDF receipt will only be used as the basis for generating PubMed Central (PMC) documents. PMC documents will be made available for review after conversion (approx. 2-3 weeks time). Any corrections that need to be made will be done at that time. No materials will be released to PMC without the approval of an author. Only the PMC documents will appear on PubMed Central --this PDF Receipt will not appear on PubMed Central. In summary, we report short practical syntheses for five labeled derivatives of DMAPP where deuterium is stereospecifically incorporated at specific protonated carbons in the molecule.
NIH Public Access
Experimental Section (R)-and (S)-[1-2 H]3-Methyl-2-buten-1-ol ((R)-and (S)-[1-2 H]1-OH)A mixture of (S)-BINOL (1.14 g, 4.0 mmol), Ti(O-iPr) 4 (1.2 mL, 1.2 mmol), CF 3 COOH (1.2 mL of 0.5 M in CH 2 Cl 2 ) and oven-dried 4 Å molecular sieves (8 g), in ether was heated at reflux for 1 h. The solution was cooled to room temperature, and [1-2 H]3 (1.02 g, 12 mmol) was added. The mixture was stirred for 5 min and cooled to −78 °C before Bu 3 SnH (4.19g, 14.4
The use of sulfones in organic chemistry, acting as an auxiliary group, is still a very important synthetic strategy, especially for the formation of carbon‐carbon single and double bonds. Once the synthetic objective is achieved, the sulfone gruop is usually removed from the molecule. This removal most commonly involves a reductive desulfonylation process with either replacement of the sulfone by hydrogen, or a process that results in the formation of a carbon‐carbon double bond when a β‐hydroxy or β‐alkoxy sulfone is employed.
This chapter is devoted to the replacement of the sulfone group by a hydrogen (reductive desulfonylation reactions), and reductive elimination reactions of Julia‐type substrates (Julia‐Lythgoe olefination process). The chapter addresses the full scope, generality, limitations, and synthetic applications of these reactions. The literature through most of 2007 is covered.
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