Isopropenyldihydrofuran derivatives. Preparation and reactions of some isopropenyldihydrofurandicarboxylates

Yamaguchi, Seiji; Sugioka, Y.; Ishida, M.; Yokoyama, Hajime; Hirai, Yoshiro

doi:10.1002/jhet.5570340439

Cited by 5 publications

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References 6 publications

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“…It is thought that this ring expansion might be caused by the ring strain due to the 5-5 fused ring system in 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylic anhydride (C), which might be formed through anhydride formation. In this paper, we describe a similar ring expansion in the lactone formation of some 2-(hydroxymethyl)-5-isopropenyl-4,5-dihydrofuran-3-carboxylic acids (1) giving corresponding 3-methyl-5,8-dihydro-1(3H)-furo [3,4-b]oxepinones (3) [2] via 2-isopropenyl-3,6-dihydro-4(2H)-furo- [3,4-b]furanones (2).…”

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confidence: 88%

“…Ethyl 2-acetyl-5-isopropenyl-4,5-dihydrofuran-3-carboxylate (6), bp ca. 100 °C (6 mmHg)(bath temperature); ir (liquid flim): 1749 (COMe), 1709 cm -1 (CO 2 Et); 1 Under cooling at -10°C, to a solution of 4 (510 mg, 2.01 mmol) in dry hexane (20 ml) was added 0.9 M methylmagnesium bromide diethyl ether solution (2.25 ml, 2.00 mmol), and the mixture was stirred at -10°C for 5 min. After treating with saturated aqueous ammonium chloride solution, the mixture was extracted with diethyl ether.…”

Section: With Equimolar Memgbr At -10°cmentioning

confidence: 99%

“…2-(1-Hydroxymethyl)-5-isopropenyl-4,5-dihydrofuran-3-carboxylic Acid (1a), colorless needles, 44%, as the fractions eluted with hexane-ethyl acetate (50:50), mp. 87-89.5 °C; ir (KBr disc): 3600-2400 (OH), 1668 cm -1 (CO 2 H); 1 To a solution of 1a,b,c (0.60 mmol) in dry benzene (5 mL) was added dicyclohexylcarbodiimide (126 mg, 0.61 mmol) and the mixture was stirred at room temperature for 30 min. After dilution with dry benzene, the filtrate was concentrated in vacuo.…”

Section: With Equimolar Memgbr At -10°cmentioning

confidence: 99%

“…In our previous paper we reported a ring expansion of 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylic acid (A) giving 6-methyl-4,7-dihydroxepin-2,3-dicarboxylic anhydride (B) [1], as shown in Scheme 1. It is thought that this ring expansion might be caused by the ring strain due to the 5-5 fused ring system in 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylic anhydride (C), which might be formed through anhydride formation.…”

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Ring Expansion of Isopropenyldihydrofuran Derivatives.

et al. 2006

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In our previous paper we reported a ring expansion of 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylic acid (A) giving 6-methyl-4,7-dihydroxepin-2,3-dicarboxylic anhydride (B) [1], as shown in Scheme 1. It is thought that this ring expansion might be caused by the ring strain due to the 5-5 fused ring system in 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylic anhydride (C), which might be formed through anhydride formation.In this paper, we describe a similar ring expansion in the lactone formation of some 2-(hydroxymethyl)-5-isopropenyl-4,5-dihydrofuran-3-carboxylic acids (1) giving corresponding 3-methyl-5,In accordance with the reported procedure [3], the starting material, diethyl 5-isopropenyl-4,5-dihydrofuran-2,3-dicarboxylate (4) was prepared through condensation of diethyl oxaloacetate with (E)-1,4-dibromo-2-methyl-2-butene. As describe in our previous paper [3], Grignard methylation of diester 4 with excess methylmagnesium bromide gave a half ester, ethyl 2-(1-hydroxy-1-methylethyl)-5-isopropenyl-4,5-dihydrofuran-3-carboxyl-ate (1c). This showed that the carbonyl might be inert for any nucleophile. Reduction of diester 4 with lithium borohydride gave another half ester, ethyl 2-(hydroxymethyl)-5-isopropenyl-4,5-dihydrofuran-3-carb-oxylate (1a'). For an approach to the third half ester, ethyl 2-(1-hydroxyethyl)-5-isopropenyl-4,5-dihydrofuran-3-carboxylate (1b'), 1a' was oxidized under Swern condition to ethyl 2-formyl-5-isopropenyl-4,5-dihydro-furan-3-carboxylate (5), and then 5 was subjected to Grignard methylation. However, the Grignard methylation of 5 with methylmagnesium bromide caused decomposition of the furan ring in any condition.

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confidence: 88%

Section: With Equimolar Memgbr At -10°cmentioning

confidence: 99%

Section: With Equimolar Memgbr At -10°cmentioning

confidence: 99%

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confidence: 96%

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Ring Expansion of Isopropenyldihydrofuran Derivatives.

et al. 2006

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ChemInform Abstract: Isopropenyldihydrofuran Derivatives. Preparation and Reactions of Some Isopropenyldihydrofurandicarboxylates.

et al. 1998

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One‐step preparation of some 2‐isopropenyl‐2,3‐dihydronaphtho‐[2,3‐b]furan‐4,9‐diones

Yamaguchi

Katsuki

Yokoyama

et al. 2001

Journal of Heterocyclic Chem

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Some 2-isopropenyl-2,3-dihydronaphtho [2,3-b]furan-4,9-diones 1a-f,b',f' were prepared by one-step cyclizations of 2-hydroxy-1,4-naphthoquinones 2a-f with 1,4-dibromo-2-methyl-2-butene (3).J. Heterocyclic Chem., 38, 511 (2001).Our recent interests were focused on the effective preparation of natural 2-isopropenyl-2,3-dihydrobenzofuran derivatives [1]. Some dehydroiso-α-lapachones 1a,b,b',f, having a 2-isopropenyl-2,3-dihydronaphtho- [2,3-b]furan-4,9-dione structure, were isolated from Cresentia cujete, and showed interesting mutagenic activities [2]. In this paper, one-step preparation of 2-isopropenyl-2,3-dihydronaphtho [2,3-b]furan-4,9-diones 1 are described.Nickl reported the first one-step preparation of 2-isopropenyl-2,3-dihydrobenzofuran derivatives; cyclization of 2',4',6'-trihydroxyacetophenone with 1,4-dibromo-2-methyl-2-butene 3 effectively gave 7-acetyl-2-isopropenyl-2,3-dihydrobenzofuran-4,6-diol in ethanol/sodium ethoxide solution [3]. But, the similar cyclization of general phenols with 3 generates only O-alkylation products in ethanol/sodium ethoxide solution. We found that the cyclization of general phenols with 3 was effective in non-polar solvents, such as ether or toluene with sodium metal or sodium hydride [1], and the cyclization of 1,3-diketones with 3 was effective in acetone with potassium carbonate [4].For the preparation of 1, a one-step cyclization of 2-hydroxy-1,4-naphthoquinones 2 with 3 was planned. The one-step cyclization was studied under several conditions using commercially available 2-hydroxy-1,4-naphthoquinone (2a), and the results are summarized in table 1. Cyclization of 2a with 3 gives none of the cyclized product in polar conditions, such as ethanol/sodium ethoxide or acetone/potassium carbonate, but gives the desired cyclized product 1a under non-polar conditions. Cyclizations using sodium hydride (2 equivalents) in refluxing ether or tetrahydrofuran, calcium hydride (2 equivalents) in refluxing toluene, and n-butyl lithium (1 equivalent) in refluxing toluene, show low yields (<4%). But, cyclization using sodium hydride (2 equivalents) in refluxing toluene shows the best yield of 16% after 24 hours. Use of equal (1 equivalent) or excess ( 3 equivalents) amounts of sodium hydride decreases the yields (1 equivalent gives 0%, 3 equivalents give 1%), and longer reaction time also decreases the yield (48 hours gives < 1%).For a preparation of the corresponding 2-hydroxy-1,4-naphthoquinones 1b-f, five methoxy-substituted 2-hydroxy-1,4-naphthoquinones 2b-f were prepared according to reported procedures [5a-e]. Four methoxysubstituted 2-hydroxy-1,4-naphthoquinones (2b-e) and

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Isopropenyldihydrofuran derivatives. Preparation and reactions of some isopropenyldihydrofurandicarboxylates

Cited by 5 publications

References 6 publications

Ring Expansion of Isopropenyldihydrofuran Derivatives.

Ring Expansion of Isopropenyldihydrofuran Derivatives.

ChemInform Abstract: Isopropenyldihydrofuran Derivatives. Preparation and Reactions of Some Isopropenyldihydrofurandicarboxylates.

One‐step preparation of some 2‐isopropenyl‐2,3‐dihydronaphtho‐[2,3‐b]furan‐4,9‐diones

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