Showing papers on "Total synthesis published in 1972"
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TL;DR: In this paper, Steviol (I) and erythroxydiol A (II), tetracyclic diterpenes with a substituent at the bridgehead C-13 position, were synthesized by using two interesting rearrangement reactions.
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TL;DR: In this paper, a convergent synthesis starting from methyl 6-bromo-4-methylhex 4-enoate (13) and 5,7-dihydroxy 4-methylphthalide (24) was presented.
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TL;DR: The first cubebane-type sesquiterpenoids were synthesized from norcubebanone as mentioned in this paper, and the stereoselective course of the synthesis provided a synthetic proof for the stereochemistry of cubebanes and cubebol.
Abstract: The total synthesis of cubebane-type sesquiterpenoids, i.e.α- and β-cubebenes (II) and (III), and cubebol (I), from (–)-trans-caran-2-one (IX), has been accomplished. Pyrolytic cleavage of carane-2-spiro-2′-tetrahydrofuran-5′-one (XII)(having a trans-carane structure) led to methyl 3-(trans-p-mentha-2,8-dien-2-yl)propionate (XV), which was converted into the corresponding diazo-ketone (XVI). Copper-catalysed decomposition of the diazo-ketone resulted in the formation of a mixture of intramolecular addition products, one of which, upon hydrogenation, gave trans-7-isopropyl-10-methyltricyclo[4,4,0,01,5]decan-4-one (norcubebanone)(XVIIIa), the key intermediate of this synthesis. Cubebenes and cubebol were synthesised from norcubebanone, and the stereoselective course of the synthesis provided a synthetic proof for the stereochemistry of these sesquiterpenoids.
TL;DR: A total synthesis of (±)-ishwarane, a tetracyclic sesquiterpenoid possessing a tricyclo[3.02,7] octane system, is described in this paper.
Abstract: A total synthesis of (±)-ishwarane, a novel tetracyclic sesquiterpenoid possessing a tricyclo[3.2.1.02,7]octane system, is described. Completion of the synthesis of ishwarane firmly establishes the...
TL;DR: In this article, two new synthetic routes to a number of tetracyclic intermediates, for the total synthesis of some diterpenoids incorporating the bicyclo[3.2.1] octane moiety, are described.
TL;DR: In this article, a novel and general synthesis of δ-lactones from glutaraldehyde is described, where the dialdehyde is first reacted with an alkyl or substituted alkyls Grignard reagent to afford a δhydroxyaldehyde in good yield.
Abstract: A novel and general synthesis of δ-lactones from glutaraldehyde is described. The dialdehyde is first reacted with an alkyl or substituted alkyl Grignard reagent to afford a δ-hydroxyaldehyde in good yield. These aldehydes exist preferentially in the cyclic hemiacetal form (δ-lactols). Oxidation of the latter compounds to give δ-lactones is readily achieved with silver oxide or bromine. The δ-lactols and δ-lactones serve as intermediates for the total synthesis of steroids.
TL;DR: In this article, the synthesis of the macrolide antibiotic (+/-)-pyrenophorin (1) is described, and a novel method of removing p-toluenesulphonylethyl esters (166) is reported as is a new simple technique of hydroxyl alkyl-ation involving molecular sieves and sodium hydrogen carbonate.
Abstract: The synthesis of the macrolide antibiotic (+/-)-pyrenophorin (1) is described. The molecular sieve promoted cyclisation of the hydroxy methyl ester (135) failed in our hands but the hydroxy-acid (190) was successfully converted to the dithioacetal of (1) using N,N'-carbonyldiimidazole (207) and 1,5-diazabicyclo(4,3,0)-non-5-ene (147). A novel method of removing p-toluenesulphonylethyl esters (166) is reported as is a new simple technique of hydroxyl alkyl-ation involving molecular sieves and sodium hydrogen carbonate.
TL;DR: The utility of the Nef reaction in the generation of cyclopentane aldehydes leading to 11-deoxyprostaglandins is reported in this paper.
TL;DR: In this article, a new total synthesis of L(+)-muscarine is described, which was resolved at the α-carbon by stereospecific hydrolysis of the N-acetyl group of the L-isomer with hog kidney acylase I.
Abstract: A new total synthesis of L(+)-muscarine is described. Performic acid oxidation of N-acetylcrotylglycine gave the corresponding 4,5-diol which was resolved at the α-carbon by stereospecific hydrolysis of the N-acetyl group of the L-isomer with hog kidney acylase I. The resulting α-L(+)-aminoacid diol (3; Chart 1) was deaminated with nitrous acid to give 4-hydroxy-5-methyl-2-tetrahydrofuran carboxylic acid with retention of configuration at position 2. Reaction of the corresponding methyl ester with dimethylamine gave two major amide constituents in 65% yield. Reduction of these two N,N-dimethylamides (5a and b) with lithium aluminum hydride followed by quaternization with methyl iodide afforded a pure isomer of L(+)-muscarine (6a) and L(+)-muscarine (6b) in high yields. The biological activity of the latter was the same as that of the natural alkaloid.