Of 4,4-dimethoxy-2-butanone with

A mixture of 3-chloro-4,4-dimethoxy-2-butanone (3.33 g, 20 mmol), benzami-dine hydrochloride (4.70 g, 30 mmol) and sodium acetate (4.10g, 50 mmol) is refluxed (42h) in dioxane (100 ml). After cooling, the salts are removed by filtration and the filtrate concentrated to an oil under reduced pressure. This oil is taken up in ethyl acetate (100 ml) and extracted with IM HQ (3 X 20 ml). The combined aqueous extracts are washed with ethyl acetate, and carefully basified with solid sodium carbonate. The aqueous solution is extracted with chloroform (3 x 20 ml), and the combined extracts are dried (MgS04), filtered and concentrated, to give the cmde product (3.23 g), which can be recrystallized from cyclohexane/toluene as fine yellow needles (2.33 g, 60%), m.p. 155-157°C. Similarly prepared are 4-acetyl-2-methyl- (46%) and 4-acetyl-2-hexylimidazoles (26%). 

Acylainino-4-acylimidazoles have been made from 3-amino-l,2,4-oxadiazoles and 1,3-dicarbonyl reagents (see Section 2.2.1 and Scheme 2.2.5). 4(5)-Acylimidazoles can be derived from 4-acylaininoisoxazoles (see Section 6.1.2 and Scheme 6.1.3). (See also the discussion in Section 2.2.1 on 4-acylimidazole synthesis.) 5-Acyl-l-arylimidazoles can be made from or-oxoketene-SJV-acetals and nitrosoaromatics (see Section 3.2 and Scheme 3.2.5), and 4-acyl-imidazoles by nitration of 1,3-dicarbonyl compounds in their enolic forms, reduction to iV-alkenylformamides and subsequent cyclization (see Section 3.2 and Scheme 3.2.4). Examples have also been isolated from reactions of 2-oximino-l,2,3-tricarbonyls and amines (see Section 4.1 and Scheme 4.1.7), from compounds such as 3-chloro-4,4-dimethoxy-2-butanone and 3,4-disubstituted 3-buten-2-ones (see Section 4.3 and Scheme 4.3.5), and by ultraviolet irradiation of 1-alkenyltetrazoles which bear an acyl group conjugated with the exocyclic double bond (see Section 6.1.2.3). 

Preparation. Wenkert and Berges1 generated the reagent in situ from 1,4-dimethoxy-2-butanone2 by reaction with ethanolic potassium hydroxide. Ireland et al.3 prepared the reagent in crude form by the pyrolysis of 1,4-dimethoxy-2-butanone with sodium benzoate.4 In a typical reaction 10.06g. of the precursor on pyrolysis with 12.5 g. of sodium benzoate afforded 4.38 g. of distillate that contained 2.7-2,8g. of methoxymethyl vinyl ketone (assayed by vpc and NMR). This crude distillate can be used directly for annelation.5... 

Dimethoxy-2-(arylimino)-2,3,6,7-tetrahydro-4//-pyrimido[6,1 -n]iso-quinolin-4-ones were N-alkylated with A-(catalytic amount of I2 in boiling 2-butanone in 13-67% yields (00MIP19). 

The three-necked flask is charged with 750 ml. of formamide, 25 ml. of water, and 50 g. of ammonium chloride (Note 2). The mixture is heated to 180-190° in an oil bath, and 400 g. (3.02 moles) of 4,4-dimethoxy-2-butanone (Note 3) is added dropwise with stirring over the course of 6 hours (Note 4). The flow of cooling water in the reflux condenser should be adjusted to a rate such that the methanol and methyl formate formed during the reaction distil out (Note 5). After all the acetal has been added, heating is continued for 1 hour (Note 6). The mixture is allowed to cool and is poured into 1 1. of IN sodium hydroxide. The resultant solution is extracted with chloroform in a liquid-liquid extractor for 24 hours. The chloroform is separated, dried over sodium sulfate, and removed by distillation through a short column on a steam bath. 

Cyclization occurred at the N-3 atom when 4-(3-bromopropylaruino)-l, 6,7,1 1 b-tctrahydro-2//-pyrimido[6,l -zz -isoquinoline was treated with NaH to give a tetracyclic derivative <2003M1271>. 9,10-Dimethoxy-2-(arylimino)-2,3,6,7-tetrahydro-4//-pyrimido[6,l- ]isoquinolin-4-ones were N-3-alkylated with iV-(ra-bromoalkyl)phthalimides in the presence of K2C03 and a catalytic amount of I2 in boiling 2-butanone in 13-67% yields <2000W020/058308>. Treatment of the 2-[(4-methoxyphenyl)methyl] derivative of 2,3,6,7-tctrahydro-l //,5//-pyrido[3,2,l-/ylqninazolinc-... 

Methyl eugenol 013,4-dimethoxy-l-allylbenzene [95-15-2] was fust characterized in 1915 as a powerful attractant for the male oriental fruit fly, Dams dorsalis, and attracts at least 60 other closely related Dams spp. Raspberry ketone [5471-51-2] or l-(4-/>-hydroxyphenyl)-2-butanone [5471-51-2] (174) is an equally powerful attractant for the melon fly, Dams mmrbitae, and the Queensland fmit fly, D. tryoni, and at least 180 other closely related Dams spp. The acetyl ester (cue-lure) (175) is more volatile and is a synthetic parakairomone especially effective for monitoring infestations by these species. Methyl eugenol and cue-lure [3572-06-3] have been used successfully in "male annihilation" of the oriental fmit fly and the melon fly by applying them to fiber board blocks or pieces of twine together with malathion or naled insecticides and distributing them over infested areas at doses of 15 g of attractant and 1 g of the insecticide per ha. 

The Reformatsky reactions of methyl or ethyl bromoacetate with 4-acetoxy-,2,24 4-benzyloxy-,2 4-tetrahydropyranyloxy-,2 4-chloro-,8 and 4,4-dimethoxy-2-butanone1418 have been carried out. The adducts were converted to mevalonolactone by hydrolysis and, in the case of the acetal reactant, by appropriate reduction and oxidation procedures. The same Reformatsky-type syntheses of mevalonolactone have also been performed using the lithium and magnesium carbanions of acetate esters5,19 25 26 and the dianion of acetic acid28,27 instead of the usual zinc reagent. The intramolecular Reformatsky reaction of 4-(bromoacetoxy)-2-butanone gives mevalonolactone directly.28 A related route to mevalonolactone involves boron trifluoride-catalyzed cycloaddition of ketene to 4-acetoxy-2-butanone followed by hydrolysis.183... 

Condensation catalyst. Muxfeldt el a I. 2 found this reagent a suitable basic catalyst for the condensation of benzaldehyde (1) with 2,2-dimethoxy-3-butanone (2) to produce the intermediates (3) and (4) and finally 4-phenylcyclopentane-l,2-dione (5). 

The rate constant for the propagation reaction was determined by the pulsed laser method [31], In order to avoid interference with the excitation of the monomer, a photo-initiator, which absorbs up to ca. 410 run, was selected, among others 2-benzyl-2-dimethylamino-l-(4-morpholinophenyl)butanone-l (Irgacure 369, Ciba). Using 2,2-dimethoxy-2-phenylacetophenone as photo-initiator, the propagation rate constants were not accessible for temperatures exceeding 20 °C. 

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