THE ACTION OF METALLIC SODIUM ON BROMINATED CYCLIC ACETALS<sup>1</sup>

Hill, Harold S.; Potter, Gavin

doi:10.1021/ja01380a030

Cited by 9 publications

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“…Earlier studies established that the action of sodium on 2-bromomethyl-1,3-dioxolane (1) in ether proceeds according to Scheme 1. 2 Similar results were obtained by Feugeas for the Grignard reagent from 2-bromomethyl-2-methyl-1,3-dioxolane. Refluxing in tetrahydrofuran yielded the corresponding βelimination compound as the sole reaction product.…”

supporting

confidence: 77%

First Reference to the Alkoxymetallation of Diisobutylaluminium and Bromomagnesium-2-vinyloxy Ethoxide to the Corresponding (1,3-Dioxolan-2-yl)methyl Organometallics

Maier¹,

Redlich²

2000

Synlett

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Diisobutylaluminium and bromomagnesium-2-vinyloxy-ethoxide add at carbonyl compounds in the manner of (1,3-dioxolan-2-yl)methyl organometallics, giving the carbon-carbon addition products. It is assumed that the aluminium and magnesium compounds of 2-vinyloxy-ethoxide are in equilibrium with the corresponding (1,3-dioxolan-2-yl)methide.Organometallic compounds, bearing a functional group at the β-position, undergo facile β-elimination. 1 This elimination is only prevented by generating the carbanion at low temperature, with a very poor leaving group X at the β-position, or in the case of a perpendicular arrangement of lone electron pair and C-X bond. Earlier studies established that the action of sodium on 2-bromomethyl-1,3-dioxolane (1) in ether proceeds according to Scheme 1. 2 Similar results were obtained by Feugeas for the Grignard reagent from 2-bromomethyl-2-methyl-1,3-dioxolane. Refluxing in tetrahydrofuran yielded the corresponding β-elimination compound as the sole reaction product. 3 On the other hand, there are a few examples in the literature on the successful addition of the Grignard reagent of 2-bromomethyl-1,3-dioxolane (1) to carbonyl compounds. Kibayashi et al. reported the generation of 3 by addition of the organomagnesium compound of 1 to the aldehyde group of a threo-configurated carbohydrate derivative. 4 Reagents and conditions: (i): Na, Et 2 O, 35°C, H 2 O, 64%; (ii): Mg, THF, r.t., RCHO, NH 4 Cl/H 2 O, 70% (100% de). Scheme 1In a preceding paper we described the preparation of the Grignard reagent from (1) and magnesium and its reaction with less reactive carbohydrate ketones in refluxing tetrahydrofuran. These uloses gave the corresponding branched chain carbohydrate derivatives in good to excellent yields (Scheme 2, path A). 5 The discrepancy in both findings caused us to approach the problem from the opposite side. Bromomagnesium-2-vinyloxy-ethoxide (4a), the product of β-elimination from (1,3-dioxolan-2-yl)-methylmagnesium bromide, was generated at room temperature (Scheme 2, path B), by addition of ethylmagnesium bromide in tetrahydrofuran to a solution of 2-vinyloxy-ethanol (2a) in tetrahydrofuran. The mixture was allowed to warm to room temperature and then a solution of ulose 6 in tetrahydrofuran was added. After refluxing for four hours the reaction was quenched. Reagents and conditions: (i): Mg, 1.0 equiv, THF, r.t.; (ii): EtMgBr, 1.0 equiv, THF, r.t.; (iii):1,2;5,6-Di-O-isopropyliden-α-D-ribo-hexofuranos-3-ulose (6), 0.2 equiv, 4h, 65°C, NH 4 Cl/H 2 O; A:64%, B:67%.

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supporting

confidence: 77%

First Reference to the Alkoxymetallation of Diisobutylaluminium and Bromomagnesium-2-vinyloxy Ethoxide to the Corresponding (1,3-Dioxolan-2-yl)methyl Organometallics

Maier¹,

Redlich²

2000

Synlett

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“…Die C-0-Einschiebung ist demnach unbedeutend und vermag das ungewohnliche Produktverhaltnis 2/3 nicht zu erklaren. Gasphase (40") 11.5 57.8 22.2 4.6 3.9 Losung (20) 9.9 53.0 24.2 11.3 1.6…”

Section: 4070unclassified

Reaktionen des Methylens mit Acetalen und Orthoestern

Kirmse

Buschhoff

1969

Chem. Ber.

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Methylen, durch Photolyse von Diazomethan erzeugt, wurde rnit Dimethoxymethan (l), 1 .l-Dimethoxy-athan (4), Trimethoxymethan (lo), 1.3-Dioxolan (14), 2-Methyl-1.3-dioxolan (20) und 2-Methoxy-1.3-dioxolan (28) in der Gasphase und in LBsung umgesetzt. Die Einschiebungsreaktionen des Methylens mit C --H-Bindungen sind struktur-und phasenabhangig. Die von mehreren 0-Alkylgruppen beeinfluBte C -H-Bindung (,,Aldehyd-Wasserstoff") reagiert nur in 4 und 20 rascher, in 1 und 28 dagegen deutlich langsamer als andere C -H-Bindungen des gleichen Molekiils. Bei allen untersuchten Acetalen und Orthoestern, ausgenommen 1, wurde Einschiebung des Methylens in C-0-Bindungen festgestellt. 4 und 20 (in geringem MaB auch 14) zeigen auBerdem Eliminierungsreaktionen unter Bildung von Vinylathern (9, 19, 26).Bei [4.$-Dialkoxyalkyl-carbenen beobachteten wir eine Alkoxyl-Wanderung zum Carben-Kohlenstoff, die als intramolekulare C -0-Einschiebung des Carbens auf-gefal3t werden kann1). Wir haben daher gepruft, ob auch bei den intermolekularen Reaktionen des Methylens rnit Acetalen und Orthoestern C-0-Einschiebung stattfindet. Daneben interessierte der EinfluB der Alkoxylgruppen auf die C -H-Einschiebung des Methylens.Ather werden von Methylen bevorzugt in a-Stellung zum Sauerstoff angegriffen 2 4). In der flussigen Phase findet man keine C -0-Einschiebungz. 4,5), jedoch wurde in der Gasphase eine Ringerweiterung des Tetrahydrofurans zu Tetrahydropyran beobachtet". C 0-Einschiebungen des b;thoxycarbonylcarbens sind bei Oxiranen, Oxetanen6) und einigen 1 ) W. Kirmse und M. Buschhoff, Chem.

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“…The preparation of 2-(2-bromoethyl)-1,3-dioxolane and 2-(2-bromoethyl)-1,3-dioxane was carried out according to an established procedure that required the addition of acrolein to a cold solution of anhydrous hydrogen bromide in an appropriate glycol (14).…”

mentioning

confidence: 99%

Analgesics: Synthesis of 1-Dioxolanoalkylnormeperidines and 1-Dioxanoalkylnormeperidines

Kriesel

Gisvold

1971

Journal of Pharmaceutical Sciences

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THE ACTION OF METALLIC SODIUM ON BROMINATED CYCLIC ACETALS¹

Cited by 9 publications

References 0 publications

First Reference to the Alkoxymetallation of Diisobutylaluminium and Bromomagnesium-2-vinyloxy Ethoxide to the Corresponding (1,3-Dioxolan-2-yl)methyl Organometallics

First Reference to the Alkoxymetallation of Diisobutylaluminium and Bromomagnesium-2-vinyloxy Ethoxide to the Corresponding (1,3-Dioxolan-2-yl)methyl Organometallics

Reaktionen des Methylens mit Acetalen und Orthoestern

Analgesics: Synthesis of 1-Dioxolanoalkylnormeperidines and 1-Dioxanoalkylnormeperidines

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THE ACTION OF METALLIC SODIUM ON BROMINATED CYCLIC ACETALS1

Cited by 9 publications

References 0 publications

First Reference to the Alkoxymetallation of Diisobutylaluminium and Bromomagnesium-2-vinyloxy Ethoxide to the Corresponding (1,3-Dioxolan-2-yl)methyl Organometallics

First Reference to the Alkoxymetallation of Diisobutylaluminium and Bromomagnesium-2-vinyloxy Ethoxide to the Corresponding (1,3-Dioxolan-2-yl)methyl Organometallics

Reaktionen des Methylens mit Acetalen und Orthoestern

Analgesics: Synthesis of 1-Dioxolanoalkylnormeperidines and 1-Dioxanoalkylnormeperidines

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THE ACTION OF METALLIC SODIUM ON BROMINATED CYCLIC ACETALS¹