Odorless substitutes for foul-smelling thiols: syntheses and applications

Node, Manabu; Kumar, Kamal; Nishide, Kiyoharu; Ohsugi, Shin‐ichi; Miyamoto, Tomoharu

doi:10.1016/s0040-4039(01)02024-x

Cited by 112 publications

(60 citation statements)

References 13 publications

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“…49 Reagent combinations of aluminum halidesthiols are useful for demethylation of aliphatic and aromatic methyl ethers. 50 In a concise route to gefitinib (61), 6,7-dimethoxyquinazoline (59) was regioselectively demethylated to give 60 by the action of PhSH and AlI 3 in 84% yield (Scheme 4B). 51 The method could not be extended to aldehydes due to the formation of hemithioacetals.…”

Section: Partial Demethylationmentioning

confidence: 99%

Application of aluminum triiodide in organic synthesis

Tian¹,

Sang²

2015

Arkivoc

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The multifaceted reactivity of aluminum triiodide (AlI 3 ) is reviewed. The oxophilic character of the Lewis acid enables the formation of coordination complexes with esters, ethers, oxiranes, diols, Noxides, and sulfoxides that decompose spontaneously to afford acids, alcohols and olefins via ester and ether cleavage, deoxygenation of oxiranes, and deoxydehydration of diols, respectively. As an iodide ion source and hydrogen iodide precursor, the reagent allows iodination and reduction of Noxides, sulfoxides and azides as well as hydroiodination of alkenes and alkynes. Aluminum enolates, generated by treatment of -haloketones with AlI 3 , provide accesses to -hydroxy ketones, 1,5-diones, and β-iodo Morita-Baylis-Hillman esters.

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Section: Partial Demethylationmentioning

confidence: 99%

Application of aluminum triiodide in organic synthesis

Tian¹,

Sang²

2015

Arkivoc

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“…The chemoselective attack of the Grignard reagent on the aldehyde 15 possessing a methyl ester functionality led to the allyl alcohol 16 (1 : 1 mixture) in excellent yield (97%). Nucleophilic demethylation of the methyl ester 16 to 17 was performed in quantitative yield under odorless conditions by the use of dodecanethiol (Dod-SH), 10) a technique recently developed in our laboratory as an odorless substitute for malodorous alkanethiols such as ethanethiol. Oxidation of the allyl alcohol 17 with pyridinium dichromate (PDC) furnished the desired 13-oxo-15,16-dinorlabda-8(17),11E-dien-19-oic acid (1a) in 38% overall yield from the trans-communic acid (3a).…”

Section: A New Synthesis Of a Potentmentioning

confidence: 99%

A New Synthesis of a Potent Cancer Chemopreventive Agent, 13-Oxo-15,16-dinorlabda-8(17),11E-dien-19-oic Acid from trans-Communic Acid.

Katoh

Tanaka

Takeo

et al. 2002

CHEMICAL & PHARMACEUTICAL BULLETIN

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A labdane-type diterpenoid, (Ϫ)-13-oxo-15,16-dinorlabda-8(17),11E-dien-19-oic acid [(Ϫ)-1a], has been revealed by Tanaka et al. to have potent cancer chemopreventive activity, i.e., the percentage of papilloma-bearing mice was reduced to 25% by the treatment of (Ϫ)-1a, compared with the control group (DMBA and TPA only).1) The acid (Ϫ)-1a, isolated from the chopped stem bark of Thuja standishii (GORD.) CARR. as a minor component, along with three new and two known diterpenoids, has the most potent activity among the isolated diterpenoids for the prevention of incipient carcinogenesis. In addition to the above plant, three other sources of the labdane diterpenoid 1a have been reported, the seeds of Platycladus orientalis, 2) the heartwood of Juniperus chinensis 3) and the pericarp of Platycladus orientalis. 4) Because this compound is in short supply from these natural sources, an efficient synthesis of 1a would be highly useful in order to further evaluate the compound's potential as a cancer chemopreventive agent. A transformation of methyl cis-communate (2b) into the methyl ester 1b has been reported, 5) however the diene isomerization required a high temperature (200°C) in a sealed tube to proceed from the 12,14-diene to the 11,13-diene and the selective oxidative cleavage of the 13-ene in the triene via ozone or osmium tetroxide-sodium periodate resulted in poor yields. Among the diterpenoids in Thuja standishii (GORD.) CARR., the trans-communic acid (3a) was isolated as the major component (ca. 10 g) from the stem bark (ca. 5 kg), and therefore was thought to be appropriate as the starting material for the preparation of 1a. Herein we describe the first efficient synthesis of 1a from the major diterpenoid 3a.The chemical conversion of methyl cis-communate (2b) into the aldehyde 4 having been reported by Barrero et al.,6) we reasoned that the aldehyde 4 would be an excellent choice as an intermediate for the synthesis of 1a (Chart 2). Following Barrero's procedure, 6) we prepared the aldehyde 4 from trans-communic acid (3a) using the selective epoxidation with MCPBA of the 12-ene in methyl ester 3b, which was obtained by methylation of the acid 3a with diazomethane. Subsequent cleavage of the resultant epoxide with periodic acid gave the aldehyde 4 in high yield (3 steps, 63%).In the transformation of the aldehyde 4 into 1a, a two carbon elongation to the aldehyde group and appropriate functional group manipulations were required. Initially, we tried constructing the methyl vinyl ketone moiety from the aldehyde using 2-methyl-1,3-dithiane as a methyl ketone equivalent. In a model experiment, the attempted dehydration of the alcohol 5, derived from 3-phenylpropanal and 2-methyl-1,3-dithiane, with mesyl chloride in the presence of pyridine gave the undesired 2-methylene-3-phenethyl-1,4-dithiepane (6), whereas in the presence of DBU as the base it afforded 2-methyl-3-phenethyl-6,7-dihydro-5H-1,4-dithiepine (7), an isomerization product of 6, as shown in Chart 3. These results showed that the migration of sulfu...

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“…However, most of thiols, such as methanethiol, ethanethiol and benzyl mercaptan, having toxicity and a foul smell, can lead to environmental and safety problems. To develop green chemistry, some new reagents substituting for thiols should be developed in organic synthesis [3][4][5][6]. Herein, a new substitute material for thiols was prepared and characterized by single-crystal X-ray diffraction.…”

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confidence: 99%

Crystal structure of 3-(bis(benzylthio)methylene)pentane-2,4-dione, C20H20O2S2

Guo

Zhu

et al. 2013

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of material K 2 CO 3 (5.50 g, 0.04 mol) was dissolved in the mixed-solvent of vacetylacetone (2.1 ml) and dimethylformamide (30 ml). The mixture was stirred for 0.5 h, and then the the CS 2 was added dropwise within 10 min. and kept stirring. After reacting for 1 h, benzyl bromide (7.5 g, 0.044 mol) was added at once. The reaction was allowed to proceed for 12 h at room temperature, and then was poured into water and resulted in lots of white precipitate. The precipitate was filtered, washed with water and dried. Colourless crystals of the title compound, which were suitable for X-ray analysis, were obtained by recrystallizing the white deposit from an anhydrous ethanol solution at room temperature over a period of several days. Experimental detailsAll non-H atoms were refined with anisotropic displacement parameters. All H atoms were generated geometrically and refined as riding atoms with d(C-H) = 0.93-0.98 Å, and U iso (H) = 1.2U eq (C) for C atoms of CH 2 and CH groups and U iso (H) = 1.5U eq (C) for C atoms of CH 3 groups. DiscussionThiols are versatile reagents and have been widely utilized in organic synthesis [1,2]. However, most of thiols, such as methanethiol, ethanethiol and benzyl mercaptan, having toxicity and a foul smell, can lead to environmental and safety problems. To develop green chemistry, some new reagents substituting for thiols should be developed in organic synthesis [3][4][5][6]. Herein, a new substitute material for thiols was prepared and characterized by single-crystal X-ray diffraction. Within the crystal structure, the geometric parameters are in the usual ranges. The distance of C8 and C9 is 1.331(3) Å, revealing the typical C=C double bond. The S1-C7 and S1-C8 bond lengths are 1.824(2) and 1.759(1) Å, respectively. The torsion angles of C1-C7-Sl-C8 and S1-C8-Sl(i)-C7(i) are 70.25(12)°and 49.36(9)°. The C10-O1 distance is 1.188(3) Å, showing the bond between the two atoms is a double bond. The molecules are held together by the van der Waals forces to form the title structure.

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Odorless substitutes for foul-smelling thiols: syntheses and applications

Cited by 112 publications

References 13 publications

Application of aluminum triiodide in organic synthesis

Application of aluminum triiodide in organic synthesis

A New Synthesis of a Potent Cancer Chemopreventive Agent, 13-Oxo-15,16-dinorlabda-8(17),11E-dien-19-oic Acid from trans-Communic Acid.

Crystal structure of 3-(bis(benzylthio)methylene)pentane-2,4-dione, C20H20O2S2

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