A General Method for the Highly Regioselective Introduction of Substituents into the 3-Position of 5-Unsubstituted 4-<i>O</i>-Alkyl Tetronates

Paintner, Franz F.; Allmendinger, Lars; Bauschke, Gerd

doi:10.1055/s-2005-918915

Cited by 13 publications

(2 citation statements)

References 3 publications

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“…The residue was purified by CC (SiO 2 , hexane -AcOEt = 100 : 0 to 85 : 15) to give 20 as a brown oil (25 mg, 37%). 9.7, 75.1, 126.2, 128.3, 128.5, 128.6, 131.5, 132.0, 133.1, 133.3, 133.7, 136.7, 156.8, 181.4, 185.7 (one C missing (16) According the reported procedure, 17 to a solution of 7 (120 mg, 0.59 mmol) and Et 3 N (0.11 mL, 0.79 mmol) in CH 2 Cl 2 (0.6 mL), TIPSOTf (0.17 mL, 0.63 mmol) was added at 0 °C and the whole was stirred at 0 °C for 1 h. The mixture was diluted with hexane (anhydrous, 3.0 mL), washed with ice-cooled aqueous half saturated NaHCO 3 (2 x 1.2 mL) and ice-cooled brine (1 x 1.2 mL), and dried over MgSO 4 .…”

Section: -Benzyloxy-3-methylnaphthalene-14-dione (20)mentioning

confidence: 99%

“…Furanone 7 was converted to furan 15, 11 which were reacted with benzyne (17) in situ prepared from iodo triflate 14 12 and n-butyllitium to give epoxynaphthalene 19, which has decomposed in the course of aqueous workup to give benzyloxynaphthoquinone 20 13 in 32% yield from 7. DAR of furan 16 and benzyne (17) in the same manner gave naphthol 22 through epoxynaphthalene 21 in 46% isolated yield.…”

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confidence: 99%

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Selective Synthesis of Benzyl Enol Ethers of β-Dicarbonyl Compounds in Basic Condition and the Application towards Synthesis of Naphthoquinones

Kumamoto¹,

Katakawa²,

Yonenaga³

et al. 2014

HETEROCYCLES

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Selective synthesis of benzyl enol ether of -tetronic acids and -dicarbonyl compounds in basic condition was examined. Benzylation of -methyl--tetronic acid with benzyl tosylate in the presence of potassium carbonate gave the corresponding benzyl enol ether exclusively. The reaction of -tetronic acid and cyclic 1,3-diketones gave the O-benzyl adducts preferentially than the C,O-dibenzylated ones. Diels-Alder reaction of furan derived the benzyl enol ether of -methyl--tetronic acid and benzyne furnished the functionalized napthoquinone derivatives. Enol ethers of -tetronic acids (4-O-alkyl -tetronates) 1 are versatile building blocks in natural product synthesis and medicinal chemistry (Figure 1). 1 Synthesis of these compounds is normally achieved by treating -tetronic acids 2 and alcohols in the presence of acid catalyst. 2 Mitsunobu reaction condition 3 and alkylation in basic condition 4 are another candidates and can be applicable to acid-sensitive substrates.The drawback of these conditions is the selectivity of C-/ O-alkylation, in which C-alkylated 3 (or C,O-dialkylated 4) -dicarbonyl compounds can be generated in this reaction system. For example, CsF-mediated O-selective alkylation of tetronic acid was achieved in high selectivity with alkyl halides with low reactivity such as ethyl iodide, however, low selectivity was observed when more reactive alkyl halide such as benzyl bromide was utilized. 4b As a part of our projects of synthetic studies of natural products including naphthoquinones such as teretifoliones B (5), 5 we have planned construction of oxygen- † This article is dedicated to Professor Victor Snieckus on the occasion of his 77th birthday.

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Section: -Benzyloxy-3-methylnaphthalene-14-dione (20)mentioning

confidence: 99%

mentioning

confidence: 99%

Selective Synthesis of Benzyl Enol Ethers of β-Dicarbonyl Compounds in Basic Condition and the Application towards Synthesis of Naphthoquinones

Kumamoto¹,

Katakawa²,

Yonenaga³

et al. 2014

HETEROCYCLES

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A General Method for the Highly Regioselective Introduction of Substituents into the 3‐Position of 5‐Unsubstituted 4‐O‐Alkyl Tetronates.

2006

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Controlling the Substitution Pattern of Hexasubstituted Naphthalenes by Aryne/Siloxyfuran Diels–Alder Additions: Regio‐ and Stereocontrolled Synthesis of Arizonin C1 Analogs

2017

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3,4‐Dimethoxybenz‐1‐yne and 2‐siloxylated furans without or with a bromine atom at C‐3 undergo Diels–Alder reactions with orientational selectivity. Hydrolysis furnished a bromine‐free or a bromine‐containing naphthalene, respectively. Bromination of the former provided a regioisomer of the latter. Either of the two compounds was processed to give a variety of unnatural naphthoquinonopyrano‐γ‐lactones. This occurred by a succession of (1) Heck coupling, (2) asymmetric dihydroxylation, (3) oxa‐Pictet–Spengler cyclization, and (4) oxidation. The fifteen monomeric naphthoquinonopyrano‐γ‐lactone structures that we prepared resemble the natural product (–)‐arizonin C1 or its C‐5 epimer. Accordingly, they represent hexasubstituted naphthalenes likewise. The sixteenth naphthoquinonopyrano‐γ‐lactone that we synthesized is a kind of dimer. Its moieties are bridged differently than those in naturally occurring naphthoquinonopyrano‐γ‐lactone dimers.

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A General Method for the Highly Regioselective Introduction of Substituents into the 3-Position of 5-Unsubstituted 4-O-Alkyl Tetronates

Cited by 13 publications

References 3 publications

Selective Synthesis of Benzyl Enol Ethers of β-Dicarbonyl Compounds in Basic Condition and the Application towards Synthesis of Naphthoquinones

Selective Synthesis of Benzyl Enol Ethers of β-Dicarbonyl Compounds in Basic Condition and the Application towards Synthesis of Naphthoquinones

A General Method for the Highly Regioselective Introduction of Substituents into the 3‐Position of 5‐Unsubstituted 4‐O‐Alkyl Tetronates.

Controlling the Substitution Pattern of Hexasubstituted Naphthalenes by Aryne/Siloxyfuran Diels–Alder Additions: Regio‐ and Stereocontrolled Synthesis of Arizonin C1 Analogs

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