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Regioselective ring cleavage of small membered lactones provides the convenient synthesis of various types of carbon homologated carboxylic acids : e. g. highly strained four-membered lactones, such as β-propiolactones or diketene give three carbon homologated β-substituted propionic is acids or 3-methylenealkanoic acids, respectively, by the regioselective attack of organometallics to their β-carbons. On the other hand, lactones with an unsaturated group at their w position, such as β-vinyl- and β-ethynyl-β-propiolactones, γ-vinyl-γ-butyrolactone or δ-vinyl-δ-valerolactone give five, six, or seven carbon homologated carboxylic acids with olefinic bond (s), respectively, by SN2' reaction of the organocopper reagents with their terminal unsaturated carbons. These lactones are extremely useful as synthetic blocks for natural product syntheses due to the selective construction of carbon skeleton and an easy conversion of the carboxylic functional group to other functional ones. The synthetic utility of the lactones is demonstrated by the following natural products : perfumes and essential oils, insect pheromones and hormones, insecticides, and macrolides.

Schwache NH- und CH-Sauren konnen mit Diketen (1) vorteilhaft in Gegenwart eines quartaren Ammoniumchlorids acyliert werden. Carbonsaureamide liefern wahlweise mit einem oder zwei Mol 1 die Produkte 3 bzw. 10. β-Ketoester und β-Diketone ergeben 12a, b bzw. 13, Amide der Acetessigsaure fuhren zu 5 oder 8. Bei der Selbstkondensation von 1 entstehen das Polymer 16 und/oder 17. Onium Salt-catalyzed Acylations with Diketene Weak NH- and CH-acids can be acylated advantageously by diketene (1) in the presence of a quaternary ammonium chloride. Carboxamides yield with one or two moles of 1 the products 3 or 10 selectively. β-Keto esters and β-diketones lead to 12a, b or 13, respectively, and acetoacetamides give 5 or 8. The polymer 16 and/or 17 is formed by self-condensation of 1.

The reaction of 2-amino-1, 5-benzodiazocines (1) with diketene (2) gave two isomeric products 3 and 4, whereas 2-amino-1, 4-benzodiazepines (16) afforded 2-acetoacetamidodiazepines (17). Treatment of the acetoacetylated derivatives (3, 4, 17) with methanolic hydrogen chloride or thionyl chloride afforded the corresponding fused pyrimidine derivatives (5, 6, 18). Thermal dehydration of both 3a and 4a, on the other hand, gave the same cyclized compound (5a), indicating that acyl migration took place in the reaction of 4a. Similarly, 17a gave the rearranged product (19a).

The UV-VIS laser irradiation of 4-penten-4-olide (1) with benzophenone (BP) or with p-benzoquinone (BQ) under an argon atmosphere afforded the acetal-type oxetanes 2-BP and 2-BQ, respectively. Only for BP was the oxetane regioisomer 3-BP obtained, actually as major product, while 3-BQ appears to be photolabile under VIS-laser photolysis conditions and thus does not accumulate in sufficient amounts for detection. Under an oxygen atmosphere, besides these oxetane products also the 1,2,4-trioxanes 5-PB and 5-BQ, the oxygen trapping products of the intermediary preoxetane triplet diradicals 12, were isolated and fully characterized. These results demonstrate that spirolactone-type 1,2,4-trioxanes as quinghaosu analogues are accessible via trapping of Paterno-Buchi triplet 1,4-diradicals by molecular oxygen. In the case of diketene as enol-lactone partner, the Paterno-Buchi reaction with BQ gave a complex product mixture even under an argon atmosphere, leading to the oxetane 6 as major product, and the spirocyclobutanone 7 and spirobioxetane 8 as minor products. Under an oxygen atmosphere also the spiroacetal 9 was obtained, but no trioxanes (oxygen trapping) could be detected in this VIS-laser photolysis. Praparative UV-VIS-Laser-Photochemie: Photocycloadditionen von Methylenlactonen mit Benzophenon und p-Benzochinon. Sauerstoffabfangreaktionen der Paterno-Buchi-Triplett-1,4-Diradikale als Modellreaktionen zur Synthese Quinghaosu-analoger 1,2,4-Trioxane Die UV-VIS-Laser-Bestrahlungen von 4-Penten-4-olid (1) mit Benzophenon (BP) bzw. p-Benzochinon (BQ) unter Argonatmosphare ergaben die Oxetane 2-BP bzw. 2-BQ mit Acetalstruktur. Das regioisomere Oxetan 3-BP wurde als Hauptprodukt nur in der Reaktion mit BP erhalten, wahrend das analoge Oxetan 3-BQ photolabil zu sein scheint und deshalb nicht nachgewiesen werden konnte. Unter Sauerstoffatmosphare konnten neben diesen Oxetanen als Sauerstoffabfangprodukte der intermediaren Praoxetan-Triplett-Diradikale 12 die 1,2,4-Trioxane 5-BP und 5-BQ isoliert und vollstandig charakterisiert werden. Diese Ergebnisse zeigen, das 1,2,4-Trioxane mit Spirolactonstruktur als Quinghaosu-Analoga durch Sauerstoffabfangreaktion von Paterno-Buchi-Triplett-1,4-Diradikalen zuganglich sind. Die Paterno-Buchi-Reaktion von Diketen als Enollacton-Partner und BQ fuhrte auch unter Argonatmosphare zu einem komplexen Produktgemisch mit dem Oxetan 6 als Hauptprodukt und dem Spirocyclobutanon 7 sowie dem Spirobioxetan 8 als Nebenprodukte. Bei der analogen Reaktion unter Sauerstoffatmosphare wurde auserdem das Spiroacetal 9 erhalten, jedoch konnten bei dieser VIS-Laser-Photoreaktion keine Trioxane (Sauerstoffabfangprodukte) nachgewiesen werden.

Reaction of diketene with ethyl pyridineformimidates (Ia-e) resulted in the formation of 6-methyl-2-pyridyl-4H-1, 3-oxazin-4-one (IVa-c) and 2-ethoxy-6-methyl-2-pyridyl-2H-1, 3-oxazin-4 (3H)-one (IIIb, c). Similar reaction with ethyl 2-quinolineformimidate (Id) and methyl 2-pyridineacetimidate (Ie) gave 6-methyl-2-(2-quinolyl)-4H-1, 3-oxazine-4-one (IVd) and 2-methoxy-6-methyl-2-(2-pyridylmethyl)-2H-1, 3-oxazin-4 (3H)-one (IIIe), respectively. The products obtained were treated with ammonia to give 6-methyl-2-substituted-4 (3H)-pyrimidone (Va-e). Hydrolysis of IIIe gave 6-hydroxy-4-methyl-3 (or 5)-(2-pyridyl)-2 (1H)-pyridone (VIII).

The synthesis of naturally occurring anthracene-9, 10-diones (12a-c) from ethyl 2-benzyl-4, 6-dihydroxybenzoates (7a-d), prepared by the reaction of diketene with ethyl 4-aryl-3-oxobutanoates (6a-d), is described. Reaction of diketene with 6a-d in the presence of sodium hydride in tetrahydrofuran gave 7a-d. Treatment of 7a-d with methyl iodide in the presence of potassium carbonate, followed by ethanolic sodium hydroxide, gave 2-benzyl-4, 6-dimethoxybenzoic acids (9a-d). Cyclization of 9a-d with trifluoroacetic acid-trifluoroacetic anhydride gave anthrone derivatives (10a-d) which, without purification, were oxidized with chromium trioxide to give the anthracene-9, 10-diones (11a-d). Selective demethylation of 11a-c with boron tribromide gave 12a-c.

Photoaddition of 2-pyridones and 2-quinolones to diketene or allene gave the head-to-tail adducts, irrespective of the kind of 4-substituent. Therefore, the adducts obtained by the photoaddition of 2-quinolone, 4-methyl-2-quinolone, and their 1-methyl derivatives to diketene (previously assigned as having the head-to-head structure) have now been determined to have the head-to-tail structure. The stereochemistry of the adducts derived from these 2-quinolones and diketene was determined by X-ray crystallographic analysis and nuclear magnetic resonance spectroscopy.

Total Synthesis of antibiotic althiomycin has been achieved starting from D-cysteine. The imide bond between thiazoline and the pyrrolinone part was constructed by coupling reaction of sodium salt of pyrrolinone with cysteine active ester or by photoreaction with diketene. The hydroxymethyl group attached on the carbon adjacent to C-2 of the thiazoline ring, was introduced by aldol condensation posterior to the thiazoline ring formation. The thiazole part was introduced in a final step in whole process of the total synthesis of the antibiotic. The synthetic althiomycin was identical with the natural antibiotic in all respects.

The reaction of diketene with cyanamide gave 2-amino-6-methyl-4H-1, 3-oxazin-4-one, which was transformed to 6-methyluracil by refluxing it in acetic acid. Diketene also reacted with monosubstituted cyanamides to give 1, 3-oxazin-4-one derivatives, which could be similarly converted into 1-substituted 6-methyluracils. The reaction of diketene with dicyanodiamide afforded 2-guanidino-6-methyl-4H-1, 3-oxazin-4-one, which, on treatment with ammonia, afforded 2-guanidino-4-hydroxy-6-methylpyrimidine.

Two types of the carbapenem key intermediates (4 and 6) have been efficiently synthesized from inexpensive (S)-ethyl lactate (7). Thus, (S)-2-benzyloxypropanal readily obtainable from 7 was condensed with di-p-anisylmethylamine to give the chiral imine. The [2+2]-cycloaddition reaction of diketene with the imine underwent in a highly stereoselective manner, yielding the desired 3,4-trans-3-acetyl-β-lactam (13a) as a major product (diastereoselectivity 7∼10:1). This was elaborated to 4 and 6 in 9 and 6 steps, respectively.

The reactions of 1-alkyl-3, 4-dihydroisoquinolines (4a-d) with 4-nitrobenzoyl cyanide (2) gave the indolizine derivatives 5a-c and 6d, respectively. Compounds 4a and 4b also reacted with diketene (8) to give the quinolizinone derivatives 9a, b, respectively.

Primary alkyl Grignard reagents react regioselectively with diketene in the presence of cobalt(II) iodide to afford 3-methylenealkanoic acids in good yields. The synthetic utility of this reaction is demonstrated in the syntheses of terpenoids by two methods. Utilizing the isomerization of double bond of 3-methylenealkanoic acids, geranic acid and farnesic acid were obtained in two steps. Another method, the tandem [3,3] sigmatropic rearrangement of the corresponding allylic esters was used for the synthesis of C18-Cecropia juvenile hormone.

13 C nuclear magnetic resonance (n.m.r.) spectra at 75.4 MHz of partially modified amylose with β-keto ester groups (degree of substitution ( DS ) ranging from 0.52 to 2.42) were studied in order to evaluate the selectivity of the reaction of amylose with diketene in the homogeneous phase. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of individual hydroxyl groups decreases in the order C-6>C-3>C-2 for DS values up to ∼1.8. For higher DS values a negative deviation is observed for the hydroxyl group at C-6 and a positive deviation for the hydroxyl groups at C-2 and C-3. The DS values determined by 13 C n.m.r. spectra are in good agreement with those found by chemical analysis.

The reaction of γ-bromoacetoacetyl bromide (1) with N-arylhydroxylamines (2) afforded N-(γ-bromoacetoacetyl)-N-arylhydroxylamines (3), which were treated with sodium methoxide to give 2-aryltetrahydro-2H-1, 2-oxazine-3, 5-dione (4). Treatment of 3 with hydroxylamine directly afforded the 5-oxime derivatives of 4 (7), which could be transformed to 4 by mild hydrolysis with dilute mineral acid.

Photolysis of acyl azides (1, 10) in diketene was investigated. Irradiation of a mixture of benzoyl azide (1a) and diketene in dichloromethane gave 1-benzoyl-4-hydroxy-3-pyrrolin-2-one (2a) in 17% yield. Similarly, reaction of diketene with p-anisoyl azide (1b), p-toluoyl azide (1c), p-chlorobenzoyl azide (1d) and ethyl azidoformate (10) gave the corresponding pyrrolinones (2b, 2c, 2d, and 11) in 7-22% yields.

Diketen (1) und die Acetessigsaureamide 3 kondensieren in Gegenwart schwacher Basen wie N,N-disubstituierter Aniline zu den 3-Acetyl-6-hydroxy-4-methyl-2-pyridonen 8, die damit leicht zuganglich sind. Die Reaktion verlauft offenbar uber eine N-Acylierung, wahrend die bekannten isomeren 3-Acetyl-4-hydroxy-6-methyl-2-pyridone 6 als Folgeprodukte einer C-Acylierung aufgefast werden konnen. A New Reaction of Diketene with Acetoacetamides In the presence of weak bases like N,N-disubstituted anilines diketene (1) and the acetoacetamides 3 condense to give 3-acetyl-6-hydroxy-4-methyl-2-pyridones 8 which thus become readily accessible. The reaction obviously proceeds via N-acylation, whereas the known isomeric 3-acetyl-4-hydroxy-6-methyl-2-pyridones 6 can be regarded as products of C-acylation.

3-Isoxazolols can be made in good yields from β-ketoesters or diketene and hydroxylamine, provided that pH is kept at about 10 throughout the reaction, and that the reaction mixture is quenched with an excess of strong mineral acid. This suppresses the formation of 5-isoxazolones, which are otherwise normally the main products of the reaction.

When diketene and sodium tetrachloropalladate(II) are mixed in aqueous solution, color of the solution changes promptly from dark red to yellow. During this fast primary reaction about one equivale...

Methylschwefelpentafluorid (5) wurde systematisch synthetisiert, ausgehend von SF5Cl und Keten. Es ist bei Raumtemperatur stabil gegen HF-Eliminierung. Die Reaktion von SF5Cl und Diketen fuhrt zu einer Vielzahl anderer Verbindungen des Typs SF5CH2X, in einfacher Weise jedoch nicht zur Titelverbindung. Methylsulfurpentafluoride and Some of its Derivatives Methylsulfurpentafluoride (5) was systematically synthesized, starting with SF5Cl and ketene. It is stable at room temperature against HF elimination. The reaction of SF5Cl and diketene gives compounds of the type SF5CH2X, but the title compound is not produced in this way.

The reactions of diketene with S, S-dimethyl-N-2-pyridinylsulfilimine (IVa) and N-2-benzothiazolyl-S, S-dimethylsulfilimine (IVb) gave 2-(2-dimethylsulfuranylideneaceto-acetamido) pyridine (VIa) and 2-(2-dimethylsulfuranylideneacetoacetamido) benzothiazole (VIb), respectively. However, the reaction of diketene with S, S-dimethyl-N-(4-nitrophenyl) sulfilimine (IVc) and N-2-benzoxazolyl-S, S-dimethylsulfilimine (IVd) gave 3-acetyl-4-hydroxy-6-methyl-1-(4-nitrophenyl)-2-pyridone (VIIc) and 3-acetyl-1-(2-benzoxazolyl)-4-hydroxy-6-methyl-2-pyridone (VIId), respectively. On the other hand, the reaction of diphenylketene with sulfilimines (IVa, IVb, and IVd) gave the corresponding 1, 3-cyclization products (VIII, IX, and X).

Photoreaction of diketene with 3-acetoxy-5, 5-dimethyl-2-cyclohexenone (1) gives 6-acetoxy-7-hydroxy-4, 4-dimethyl-cis-bicyclo [4.2.0] octan-2-one-7-acetic acid β-lactone (2 and 3). Treatment of 2 with dimethylamine affords 3-acetoxy-7-hydroxy-N, N, 4, 4-tetramethyl-cis-bicyclo [4.2.0] octan-2-one-7-acetamide (4), while similar treatment of 3 affords 1-acetoxy-N, N, 4, 4-tetramethylcyclooctane-2, 6-dione-1-acetamide (5). This result suggests the spiro-configuration of 2 is the trans (acetoxy and oxetane O), while that of 3 being the cis.

The corresponding acetoacetylated 2,2′-anhydro-N3-nucleosides were obtained from diketene and arabinose, xylose, and ribose aminooxazolines. The protective groups were removed, and the anhydro bond was cleaved. The structures and reactivities of the intermediate — 2,2′-anhydro-3-β-D-arabinofuranosyl-6-methyl-5,6-dihydrouracil — were studied.

Reaction of several conjugated C-N double bond compounds with diketene was carried out with a view to establishing the structure-reactivity relationship of the 1, 3-diaza-1, 3-butadiene system. Formamidine derivatives (IIIa-h) reacted with diketene in benzene to form the products (Va-h) through 1, 4-dipolar cycloaddition with the elimination of dimethylamine, respectively. Similarly, reaction of diketene with 2-(p-dimethylaminobenzylideneamino) benzothiazole (IXa) and 2-(p-dimethylaminobenzylideneamino) benzimidazole (IXb) respectively afforded 3-acetyl-2-(p-dimethylaminophenyl)-2, 3-dihydro-4-oxo-4H-pyrimido [2, 1-b] benzothiazole (Xa) and 3-acetyl-2-(p-dimethylaminophenyl)-2, 3-dihydro-4-oxo-4H-pyrimido-[1, 2-a] benzimidazole (Xb).

Acylation of the N-substituted diethyl aminomalonates 3a – 3d with diketene furnished the ring tautomers 6a – 6d of the expected acetoacetyl derivatives 5 . By treatment with iodine and sodium ethoxide compounds 6a – 6d are smoothly converted into the β-lactam derivatives 2a – 2d . Deethoxycarbonylation of the ethylene ketals 7a – 7d of the latter furnishes mixtures of the corresponding diastereomeric monoesters 8 and 10 . The ethoxycarbonyl groups of the trans esters 8 are more reactive than those of the cis isomers 10 . This permits, under appropriate conditions, selective alkaline hydrolysis and NaBH 4 reduction of the trans esters 8 in the presence of the cis esters 10 . Reduction of the cis ester 10c under more forceful conditions furnishes the trans hydroxymethyl derivative 11c .

1,2-Dimethylindol (1) reagiert in Gegenwart von AlCl3 mit Malonsauredichlorid zum Hydroxyazapseudophenalenon 2, mit Propiolacton zur Saure 3, die als Saurechlorid unter Friedel-Crafts-Bedingungen das Keton 5 ergibt. 1 und Diketen in Eisessig fuhren mit nachfolgender Cyclisierung zum Azapseudophenalen-3-on 6, aus 6 sind mit C-Nucleophilen die Azapseudophenafulvene 7 so-wie 8, mit Cyclopentadiendicarbonitril das Azapentapseudophenafulvalen 9a zuganglich. Thionierung von 6 und Alkylierung ergibt das Azapseudophenaleniumsalz 10, aus 11 wird durch Methylierung das N-Methylazapseudophenalen-5-on 12, daraus das Thion 13, das Azapseudophenafulven 14 und die Azapseudophenaleniumsalze 15, 16 erhalten. 1-Benzoylamino-5-hydroxynaphthalin (17) wird zu 18 cyclisiert, daraus nach Verseifung zu 19 und dessen Methylierung das Azapseudophenalen-5-on 20 synthetisiert. Heterocyclic 12-π- and 14-π-Systems, 391a). — Syntheses and Chemistry of New Indole Systems; Scope and Limitations1b) 1,2-dimethylindole (1) reacts in the presence of AlCl3 with malonyl dichloride to give the hydroxyazapseudophenalenone 2, with propiolactone to give the acid 3, which as an acid chloride under the conditions of Friedel-Crafts reaction yields the ketone 5. Compound 1 and diketene lead in acetic acid and subsequent cyclisation to the azapseudophenalen-3-one 6 which, with C-nucleophiles, gives the azapseudophenafulvenes 7, 8 and with cyclopentadienedicarbonitrile the azapentapseudophenafulvalene 9a. Thionation of 6 and alkylation yield the azapseudophenalenium salt 10. Methylation of 11 affords the N-methylazapseudophenalen-5-one 12. Thionation of 12 furnishes the thione 13, the azapseudophenafulvene 14, and the azapseudophenalenium salts 15, 16. 1-Benzoylamino-5-hydroxynaphthalene (17) undergoes cyclisation to give 18 which, on saponification, affords 19 and on methylation the azapseudophenalen-5-one 20 in good yields.

The increasing use of complex organic pigments has generally focused interest on more economic pathways for their chemical synthesis. This is particularly true for the red quinacridone pigments, whose large-scale application has so far been hindered by technical difficulties connected with conditioning and the complicated multistage chemical synthesis. Recently different new synthesis routes have been developed, and that based on the chlorination of diketene has a good chance of supplanting the existing manufacturing process based on diethyl succinate.

Diketene-acetone adduct (1) generates acetylketene (2) under heating. In order to compare the reactivity of 2 with that of diketene, the reaction of 1 with electron-rich olefins was investigated. On heating with 1, primary enamines (3a-d) produced the corresponding 3-substituted 2, 6-dimethyl-4 (1H)-pyridones (4a-d), while the tertiary enamine 3e gave the 4-pyrone derivative (7). The reaction of 1 with ketene acetals (8) gave the 2, 2-diethoxy-2, 3-dihydro-4-pyrone derivatives (9). The vinyl ether derivatives 13 similarly reacted with 1 to give the 4-pyrone derivative 15 or 16 as the major product. The result shows that both diketene and 2 react with electron-rich olefins in a similar manner.

The best method to prepare N-acylpyroglutamic acids is to react N,O-bistrimethylsilylpyroglutamic acid with acid chlorides or a diketene. These acyl acids display bactericide and fungicide properties against several microorganisms.

Die Titelverbindungen 1a–e wurden mit Alkoholen, Aminen und Ammoniak zur Reaktion gebracht. Alkohol reagiert ohne Katalysator bzw. in Gegenwart von Dibutylzinn(IV)-dilaurat mit den Isocyanatgruppen selektiv zu Urethanen (5a–e), in Gegenwart basischer bzw. nucleophiler Katalysatoren auch mit den Diketen-gruppen zu s-Ketoestern (6b′). Auch mit Aminen reagieren die Isocyanatgruppen bevorzugt zu 3, 4. Die 2:1-Umsetzungsprodukte mit Alkoholen 5a–e sind weiteren aus der Chemie der Diketene bekannten Reaktionen zuganglich. Diisocyanatodiketene mit s-Lactonstruktur (1a–e) stellen somit neuartige trifunktionelle Grundbausteine abgestufter Reaktivitat u.a. fur die Synthese von Makromolekulen dar. The title compounds 1a–e were treated with alcohols, amines, and ammonia. Alcohols react without catalyst or with, e.g., dibutyltin(IV) dilaurate only at the two isocyanate groups to give urethanes (5a–e) heaving an intact diketene group, in the presence of, e.g., tert. amines or tributylphosphane the latter too react to yield a s-ketoester (6b′). Amines also react preferentially with the isocyanate groups to form 3, 4 but no react selectivity could be observed. The 2:1 reaction products of alcohols and diisocyanatodiketenes 5a–e are susceptable to reactions known from the chemistry of diketenes. The new diisocyanatodiketenes 1a–e therefore represent a new class of trifunctional building blocks for step growth polymers.

1-Oxacephem skeletons were constructed in a convergent manner starting from building blocks B and C , which were easily prepared from penicillin and diketene, respectively, followed by intramolecular carbene insertion reaction of the resulting intermediate A .

The reaction of diketene with diazoacetone (2) in the presence of benzophenone under irradiation afforded trans-1-acetyl-5-oxo-4-oxaspiro [2, 3] hexane (3) in 22% yield. Similarly, the photolysis of diketene and 2-diazoesters such as ethyl 2-diazo-3-oxo-butanoate (4a) and ethyl 2-diazo-3-oxohexanoate (4b), followed by treatment with absolute methanol saturated with dry hydrogen chloride gave diesters ; e.g., methyl 3, 6-dioxo-5-ethoxycarbonylhexanoate (8a) (39%) and methyl 3, 6-dioxo-5-ethoxycarbonylnonylate (8b) (30%), and/or furan derivatives ; e.g., 3-ethoxycarbonyl-5-methoxycarbonylmethyl-2-methylfuran (9a) (35%) and 3-ethoxycarbonyl-5-methoxycarbonylmethyl-2-propylfuran (9b) (33%). A similar reaction of diketene with di-tert-butyl diazomalonate (10) gave rise to dimethyl 2-methoxycarbonyl-4-oxohexane-1, 6-dioate (12) in 58% yield.

Alternative pathways for the thermolysis of diketene were investigated with a semiempirical SINDO method [1]. Transition states and activation energies for isomerization to cyclobutane-1,3-dione and 2,4-dimethylene-1,3-dioxetane were determined. The dissociation and formation of these three dimers into and from two ketenes was also calculated. The results disclose the possibility of existence of intermediates as well as the fragmentation into further products. Entropy appears as a major factor in this reaction at higher temperature.

The reaction of 2, 2, 6-trimethyl-1, 3-dioxin-4-one (diketene-acetone adduct) (1) with imines was investigated. Heating of the adduct 1 with N-(1-phenylethylidene) aniline (6a) gave 6-methyl-1, 2-diphenyl-4-(1H)-pyridone 7a. Similar treatment of N-benzylideneaniline (3a) gave 3, 4-dihydro-6-methyl-2, 3-diphenyl-2H-1, 3-oxazin-4-one (4a). N-Benzylidenealkylamines likewise reacted with the adduct 1 to give the corresponding 1, 3-oxazine derivative 4. Reaction of diketene with N-benzylidenealkylamines in the presence of triethylamine gave the corresponding 1, 3-oxazine along with 3-acetyl-1-alkyl-4-phenylazetidin-2-one (8).

The reaction of (CH3)3SiCH2MgCl with diketene yields 3-trimethylsilylmethyl-3-butenoic acid (1) in the presence of a catalytic amount of NiCl2(95%), PdCl2(68%), CoCl3(60%), or CuI(20%) under moderate conditions. The acid, 1, is isomerized to the conjugated acid, 4-trimethylsilyl-3-methyl-2-butenoic acid (2) by means of an excess LiN(SiMe3)2. The rearrangement proceeds stereoselectively to 2-(E) isomer by addition of diglyme or N,N,N′,N′-tetramethylethylenediamine. This is the first example of the vinyl-oxygen bond cleavage of diketene.

The best method to prepare N-acylpyroglutamic esters is to react N-trimethylsilylpyroglutamic esters with acid chlorides or diketene. These acylesters possess bactericide and fungicide properties against several microorganisms.

Monocyclic β-lactam, d1-1 prepared by the diketene cycloaddition method was subjected to microbial transformation to give 3,4-trans-(R), (S)-OH mixture 2 and 3,4-cis-(R)-OH 3 and 3,4-cis-(S)-OH 4 depending on the microorganisms.

La pyrolyse de la trimethyl-2,2,6 4H-dioxinne-1,3one-4 en presence de nucleophiles constitue une bonne methode de preparation de derives acetylacetates

Photoreaction of diketene with 4-methyl-2(1H)-quinolone and 1,4-dimethyl-2(1H)-quinolone gave 2R*,2aR*,SbR*- and 2R*,2aS*8bS*-8b-methyl-3-oxo-1,2,2a,3,4,8b-hexahydrocyclobuta[c]quinoline-2-spiro-2′-(oxetan)-4′-one (6a and 6b), and their 4-methyl derivatives 7a and 7b, respectively. Thermolysis of compounds 6 and 7 afforded 2aR*,8bS*-8b-methyl-2-methylene-3-oxo-1,2,2a,3,4,8b-hexahydrocyclobuta[c]quinoline (8) and its 4-methyl derivatives 9, respectively. Similarly, photolysis of diketene and 4-acetoxy-2(1H)-quinolone gave 1R*,2aS*,8bS*- and 1R*,2aR*,8bR*-8b-acetoxy-3-oxo-1,2,2a,3,4,8b-hexahydrocyclobuta[c]-quinoline (11a and 11b). Alcoholysis of compounds 11a and 11b with hydrogen chloride in methanol gave 1-hydroxy-1-(methoxycarbonyl)methylcyclobuta[c]quinoline derivative 12 and 13 which were transformed to 4-acetyl-3-methyl-2(1H)-quinolone (15) by further alcoholysis. Photoreaction of diketene with 2(1H)-quinolone derivatives gave the corresponding cyclobuta[c]quinoline spirooxetanone derivatives 18 and 23, which, by thermolysis, were transformed to 2-methylenecyclobuta[c]quinoline 23 and 25, respectively.

The reaction of diketene (1) with some organometallics was investigated. The reaction of 1 with benzyl Grignard reagents in the presence of nickel (II) chloride afforded 3-benzyl-3-butenoic acids 2a-e. In the presence of dichloro [1, 3-bis (diphenylphosphino) propane] nickel, primary alkylmagnesium bromides reacted with 1 to give 3-methylenealkanoic acids 2g-i. (E)-1-Alkenyldiisobutylaluminiums, in the presence of Pd (0)-catalyst, reacted with 1 to give 3-methylene-4-alkenoic acids 5a-c. Similarly, alkynyl-and aryl-zinc chlorides gave 3-methylene-4-alkynoic acids 7a-d and 3-aryl-3-butenoic acids 8a-c, respectively.

A study has been made on the modification of poly (vinyl alcohol) with diketene using tertiary amines as catalysts. The structure of the resulting polymers was determined by means of IR, 1H- and 13C-NMR spectroscopy as well as by chemical analysis. Vinyl alcohol-vinyl acetoacetate (VAL-VAA) copolymers were obtained. It has been found a linear dependence of reaction rate on polymer, diketene and pyridine concentrations, respectively. The activation energy was found to be 35.5 kJ/mol (8.5 kcal/mol). 13C-NMR spectroscopy was used for the determination of the sequence distribution in VAL-VAA copolymers. The obtained results show that VAA units have a little alternating tendency in the copolymer chain. Polymeric chelates between VAL-VAA copolymers and cupric ions have been prepared. It is noteworthy that not all the β-keto ester groups in the VAL-VAA copolymers participate in binding cupric ions.

The reactions of diketene-acetone adduct (2, 2, 6-trimethyl-1, 3-dioxin-4-one) (1) with heteroxyclic ylides were investigated. Heating of the adduct with isoquinolinium bis (ethoxycarbonyl) methylide (3a) gave ethyl 1-acetyl-2-hydroxypyrrolo [2, 1-a] isoquinoline-3-carboxylate (6a). Under similar conditions, isoquinolinium cyano (ethoxycarbonyl)-methylide (3b) and phenacylide (3d) gave 1-acetyl-2-ethoxycarbonyloxypyrrolo [2, 1-a]-isoquinoline-3-carbonitrile (7) and 1-acetyl-3-benzoyl-2-hydroxypyrrolo [2, 1-a] isoquinoline (6d), respectively. Isoquinolinium dicyanomethylide (3e) reacted with the adduct in a different manner to give bis (6-methyl-4-oxo-4H-1, 3-oxazin-2-yl) methylide (8). Pyridinium ylides similarly reacted with the adduct to give indolizines and oxazinylmethylides.

A highly efficient synthesis of the title compound was accomplished employing the addition of diketene to chiral imine as a key stereoselective reaction and using inexpensive ( S )-ethy1 lactate as a starting material.

The reaction of benzimidazoline-2-thione (2) with diketene (1) gave the oxazine derivative 3 and the thiazine derivative 4. However, the reaction of 2-indolinethione (6) with diketene afforded only the thiazine derivative 7. On the other hand, no cyclized compound was obtained from 2-indolinone (8) and diketene. The reactions of N, N'-diphenylthiourea (11) and 2-aminobenzothiol (14) with diketene were also studied ; 11 and 14 gave the thiouracil 12 and the benzothiazine 16, respectively.

This paper describes addition reaction of exo-methylene double bond of diketene to give the product keeping the β-lactone ring intact. Emphasis is placed on the reaction with double bond compounds such as olefin, carbonyl, and azo compounds to give the spiro-oxetanones.

Ethyl N-(2-pyridyl) formimidate (Va) reacted with diketene to give 3-acetyl-4H-pyrido [1, 2-a] pyrimidin-4-one (VIIa) and ethyl 2-(2-pyridylaminomethylene) acetoacetate (VIIIa). Reaction of diketene with ethyl N-(2-pyridyl) acetimidate (Vb) and ethyl N-(2-pyridyl) propionimidate (Vc) afforded 4H-pyrido [1, 2-a] pyrimidine derivatives (VIIb and VIIc), respectively. Similarly 2-benzylideneaminopyridine (VIa) reacted with diketene to give 3-acetyl-4-hydroxy-2-phenyl-4H-pyrido-[1, 2-a] pyrimidine (XI). On the other hand, reaction of trimethylsilyl isocyanate with Va, Vb, and Vc gave rise to 4H-pyrido [1, 2-a]-sym-triazin-4-one derivatives (XIXa, XIXb, and XIXc), respectively. Reaction of phenyl isocyanate with VIa afforded 2, 3-diphenyl-4H-pyrido [1, 2-a]-sym-2, 3-dihydrotrazin-4-one (XX).