Fragmentierungsreaktionen and Carbonylverbindungen mit β‐ständigen elektronegativen Substituenten, XXV. 5,5‐Dimethyl‐6‐tosyloxy‐3‐hexen‐2‐on, ein vinyloges β‐Tosyloxyketon

Marschall, Helga; Tantau, Karl; Weyerstahl, Peter

doi:10.1002/cber.19741070315

Cited by 9 publications

(3 citation statements)

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“…26 The Oalkylation to 3,3,6-trimethyl-3,4-dihydropyran-4-carbonitrile has also been reported as a competitive reaction of 5,5-dimethyl-6-(tosyloxy)-3-hexen-2-one with potassium cyanide. 14 In an effort to extend the scope of these MIRC reactions, the reaction of w-chloroalkylidenes 3 with isopropylamine and hydride was also studied. Reaction of malonate 3a with isopropylamine in diethyl ether at room temperature did not lead to the formation of the target cyclobutane (Scheme 4).…”

Section: Methodsmentioning

confidence: 99%

“…Early research was performed on the synthesis of 1,1-dicyanocyclobutanes and alkyl 1-cyanocyclobutane-1-carboxylates by reaction of doubly activated w-tosyloxyolefins with hydride or alkoxide, 13 and on the synthesis of 2-methoxy-and 2-cyanocyclobutyl ketones, together with cyclohexenones and dihydropyrans as side products, from 5,5-dimethyl-6-(tosyloxy)-3-hexen-2-one. 14 Dialkyl cyclobutane-1,1-dicarboxylates have not been prepared, because the required dialkyl w-tosyloxyalkylidenemalonate could not be prepared via standard Knoevenagel condensation of 3-tosyloxy-2,2-dimethylpropanal with diethyl malonate which was insufficiently reactive. 13 Following this pioneering research on MIRC-based cyclobutane synthesis, only two additional isolated examples have been reported which involved cyclization of alkyl 5-bromo-or 5-iodo-2-pentenoates, i.e.…”

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Synthesis of Functionalized Dialkyl Cyclobutane-1,1-dicarboxylates and Alkyl 5,6-Dihydro-4H-pyran-3-carboxylates via Michael-Induced Ring Closure of δ-Chloro-α,β-Unsaturated Diesters and Ketoesters

Mangelinckx¹,

Vermaut²,

Verhé³

et al. 2008

Synlett

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Michael-induced ring closure (MIRC) of dimethyl 2-(3chloro-2,2-dimethylpropylidene)malonate, upon treatment with sodium tert-butylthiolate, sodium methoxide or sodium cyanide in methanol, provided a short and efficient synthesis of new 2-functionalized cyclobutane-1,1-dicarboxylic esters. Under similar conditions, methyl 2-acetyl-5-chloro-4,4-dimethylpent-2-enoate afforded 4-functionalized methyl 5,6-dihydro-4H-pyran-3-carboxylates as the MIRC products.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Synthesis of Functionalized Dialkyl Cyclobutane-1,1-dicarboxylates and Alkyl 5,6-Dihydro-4H-pyran-3-carboxylates via Michael-Induced Ring Closure of δ-Chloro-α,β-Unsaturated Diesters and Ketoesters

Mangelinckx¹,

Vermaut²,

Verhé³

et al. 2008

Synlett

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“…Aldehyde 9 (930 mg, 3.52 mmol), dissolved in 5 mL of THE, was then added, and the reaction mixture was stirred at 10 °C for 15 min. Quenching with dilute AcOH and extraction with Et^O gave a crude product, which was purified on silica gel (hexane-AcOEt-AcOH, 85:15:1) to give 990 mg (85%) of 1: bp 125-130 °C (0.03 mm); IR (film) 1710 cm"1; NMR (CDC13) 0.89 (t, 3, J = 7 Hz), 1.19 (s, 6), 1.24-1.42 (m, 6), 1.66 (m, 2), 2.0-2.17 (m, 4), 2.34 (t, 2, J = 7 Hz), 2.75-2.88 (m, 4), 5.11-5.20 (m, 2), 5.30-5.47 (m, 4), 5.50-5.61 (m, 2); 13C NMR (CDC13) 14 Methyl 8-Hydroxy-5(Z)-octenoate (11). hydroxy-5-octynoate8 (10; 5.3 g, 31.2 mmol) in THE (75 mL) containing Et3N (1.5 mL) was hydrogenated at room temperature and 1 atm over 530 mg of Lindlar catalyst (Aldrich Chemical Co.).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of three potential inhibitors of leukotriene biosynthesis

Pfister¹,

Murthy²

1983

J. Med. Chem.

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The syntheses of 7,7-dimethyl- (1), 10,10-dimethyl- (2), and 5,6-benzoarachidonic acid (3), potential substrate analogue inhibitors of leukotriene biosynthesis, are described. Two of these compounds (1 and 2) apparently stimulated, while 3 inhibited, the activity of lipoxygenase from intact human polymorphonuclear leukocytes in vitro when stimulated with Ca2+ and calcium ionophore A23187 in the presence of BSA and arachidonic acid.

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Synthetic Applications of Phosphoryl‐Stabilized Anions

1977

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The successful synthesis of a wide variety of unsaturated compounds by treatment of phosphoranes with carbonyl compounds (the Wittig reaction) has stimulated the search for other synthetic methods that employ organophosphorus reagents. One of the most fruitful results has been the discovery that phosphoryl‐stabilized carbanions have wide applicability in the preparation of unsaturated compounds and offer significant advantages over conventional procedures. This review discusses the chemistry of carbanions stabilized by delocalization of their negative charge by means of a P(O) group. Carbanions obtained by treating phosphine oxides, phosphinates, and phosphonates, with a base have been explored in depth. In particular, the phosphonates have found great popularity because of their availability and ease of application. The use of Wittig‐type reagents in synthesis has been reviewed and is not mentioned except by way of comparison. Carbanions prepared from phosphinates have no known advantage over those prepared from phosphonates or phosphine oxides. Those carbanions obtained from phosphine oxides will be considered here only in the way of comparison. Anions that have their negative charge located on an atom adjacent to a P(O) group gain stability owing to delocalization of the charge through the phosphoryl group. Although the exact nature of the delocalization is not well defined, the ability of phosphorus to become pentacovalent by use of its d orbitals is undoubtedly a contributing factor. It should be noted that the P(O) group is generally not so effective as the carbonyl group in stabilizing a negative charge. If other stabilizing groups are not present, formation of P(O)‐stabilized carbanions generally requires more basic conditions than does the removal of a proton from a carbon atom alpha to a carbonyl group. Horner and co‐workers were the first to investigate the synthetic utility of P(O)‐stabilized carbanions. The utility of phosphonate carbanions as synthetic intermediates was expanded by the discovery that, as olefin‐forming reagents, phosphonates have certain advantages over both phosphoranes and phosphine oxides. As a result, the method has found favor because of the availability of reagents, ease of workup, and convenient reaction conditions. In particular, the reactivity of phosphonate carbanions has been taken advantage of in numerous ways. As indicated by a number of reviews, these carbanions have become one of the most frequently employed organophosphorus reagents. The utility of phosphoryl‐stabilized anions is apparent from the variety of materials that can be prepared by suitable structural modifications. Besides simple monoolefins and polyenes, a partial list would include allenes, unsaturated amides, aldehydes, esters, sulfides, sulfones, and nitrogen compounds such as imines, isocyanates, and ketenimines. In addition to their convenience for introducing unsaturation, these stabilized anions offer routes to cyclopropanes and heterocyclic systems. In this chapter, reactions that are of unusual interest are discussed separately; more routine reactions are included only in the tabular survey. Olefin formation by means of phosphonate carbanions has been referred to as the Horner‐Emmons or Wadsworth‐Emmons modification of the Wittig reaction, whereas the use of phosphine oxide or phosphinate carbanions is generally referred to as the Horner modification. In order to prevent confusion and to avoid misdirecting credit, proper names are omitted and the synthesis of an olefin by phosphonate carbanions is termed phosphonate‐olefin formation. Likewise, the term phosphine oxide‐olefin formation is employed where appropriate.

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Fragmentierungsreaktionen and Carbonylverbindungen mit β‐ständigen elektronegativen Substituenten, XXV. 5,5‐Dimethyl‐6‐tosyloxy‐3‐hexen‐2‐on, ein vinyloges β‐Tosyloxyketon

Cited by 9 publications

References 9 publications

Synthesis of Functionalized Dialkyl Cyclobutane-1,1-dicarboxylates and Alkyl 5,6-Dihydro-4H-pyran-3-carboxylates via Michael-Induced Ring Closure of δ-Chloro-α,β-Unsaturated Diesters and Ketoesters

Synthesis of Functionalized Dialkyl Cyclobutane-1,1-dicarboxylates and Alkyl 5,6-Dihydro-4H-pyran-3-carboxylates via Michael-Induced Ring Closure of δ-Chloro-α,β-Unsaturated Diesters and Ketoesters

Synthesis of three potential inhibitors of leukotriene biosynthesis

Synthetic Applications of Phosphoryl‐Stabilized Anions

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