Buten 4-methoxy

Like butadiene, allene undergoes dimerization and addition of nucleophiles to give 1-substituted 3-methyl-2-methylene-3-butenyl compounds. Dimerization-hydration of allene is catalyzed by Pd(0) in the presence of CO2 to give 3-methyl-2-methylene-3-buten-l-ol (1). An addition reaction with. MleOH proceeds without CO2 to give 2-methyl-4-methoxy-3-inethylene-1-butene (2)[1]. Similarly, piperidine reacts with allene to give the dimeric amine 3, and the reaction of malonate affords 4 in good yields. Pd(0) coordinated by maleic anhydride (MA) IS used as a catalyst[2]. 

Isoprene reacts with a-chloroalkyl ethers in the presence of ZnCl in diethyl ether from 0—10°C. For example,a-chloromethyl methyl ether at 10°C gives a 6 1 ratio of the 1,4-adduct, (F)4-chloro-l-methoxy-2-methyl-2-butene, to the 1,2-adduct, 2-chloro-l-methoxy-2-methyl-3-butene. Other a-chloroalkyl ethers react in a similar manner to give predominately the 1,4-addition product. A wide variety of aHyUc chlorides and bromides and a-chloroethers and esters add primarily 1,4- to isoprene in the presence of acid catalysts (8). 

Reductive Coupling of 4-Methoxy-a,ct,OrTnfIuoroacetophenone cis-and trans-l,1,1,4,4,4-Hexafluoro-2,3-bis(4-methoxyphenyl)-2-butene [67 ... 

Of greater importance is the reaction of unsaturated compounds with sulfur at 200-250°C, which normally leads to l,2-dithiole-3-thiones (trithiones) but especially with 2-aryIsubstituted 2-butenes and 1- aryl- or 2-aryl-1-butenes, thiophenes are obtained in 15-60% Thus p-methoxy-a-ethylstilbene (50) gives 2-phenyl-3-... 

The Diels-Alder reaetion between methoxydienie aleohol 177 [obtained by re-duetion of 1 -methoxy-1 -buten-3-yn-5-ol (176), the produet of the 1 -methoxybut-1 -en-3-yne Favorsky eondensation with formaldehyde] and 178 leads to the pyridazine 179 [84JCS(P1)1981]. 

Long-range coupling between protons more than two carbon atoms apart is sometimes observed when v bonds intervene. An example is found in l-methoxy-l-buten-3-yne. Not only does the acetylenic proton, Ha, couple with the vinylic proton H, it also couples with the vinylic proton Hc, four carbon atoms away. The data are ... 

Z)-2-Butenylpotassium is generated from 4.5 mL (50 mmol) of (Z)-2-butene, 2.8 g (25 mmol) or /-BuOK. and 10.8 mL (25 mmol) oT 2.3 M butyllithium in THF for 15 min at —45 JC. This solution is cooled to — 78 C and 30 mmol of a 1 M solution of methoxy(diisopinocampheyl)borane in diethyl elher is added dropwise. The mixture is stirred for 30 min at — 78 °C, then is treated with 4mL (33 mmol) of boron trifluoride-diethyl ctherate complex this removes methoxide from the intermediate ate complex. This solution is immediatelv treated with 35 mmol of an afdchyde. Isolated yields of homoallylic alcohols are 63-79%. 

The cyclohexyloxy(dimethyl)silyl unit in 8 serves as a hydroxy surrogate and is converted into an alcohol via the Tamao oxidation after the allylboration reaction. The allylsilane products of asymmetric allylboration reactions of the dimethylphenylsilyl reagent 7 are readily converted into optically active 2-butene-l, 4-diols via epoxidation with dimethyl dioxirane followed by acid-catalyzed Peterson elimination of the intermediate epoxysilane. Although several chiral (Z)-y-alkoxyallylboron reagents were described in Section 1.3.3.3.3.1.4., relatively few applications in double asymmetric reactions with chiral aldehydes have been reported. One notable example involves the matched double asymmetric reaction of the diisopinocampheyl [(Z)-methoxy-2-propenyl]boron reagent with a chiral x/ -dialkoxyaldehyde87. 

Aus 2-Methoxy-4-oxo-4-phenyl-buten-(2) erhalt man auf analoge Weise 92% d.Th. 3-Oxo-l-phenyl-buten3. Sind weitere mit Lithiumalanat reduzierbare Gruppen vorhan-den, so wird vor allem Natriumboranat eingesetzt z.B.4 ... 

Anilino-3-(4-dimethylamino-anilino)- 2-Anilino-3-(4-methoxy-anilino)-buten-(2)-saure-anilid 2-Anilino-3-(4-methoxy-anilino)-buten-(2)-saure-2,5-dimethyl-anilid... 

Thiophenol Benzenethiol (8, 9) (108-98-5) 4,4-Bis(phenylthio)-3-methoxy-l-butene Benzene, 1, T-[(2-meth-oxy-3-butenylidene)bis(thio)]bis- (9) (60466-65-1)... 

Catalytic systems at very low metal loading 0.1% (w/w) obtained in this way can be conveniently used in the hydrogenation of a,P-unsaturated ketones to the corresponding saturated carbonyl compounds with very high efficiencies and selectivities. In Table 4 we report the results obtained in the selective hydrogenation of 4-(6-methoxy-2-naphthyl)-3-buten-2-one, 1, and 2-acetyl-5,8-dimethoxy-3,4-dihydronaphthalene, 2, to the corresponding saturated carbonyl products (I), which are important intermediates... 

The hydroboration of enynes yields either of 1,4-addition and 1,2-addition products, the ratio of which dramatically changes with the phosphine ligand as well as the molar ratio of the ligand to the palladium (Scheme 1-8) [46-51]. ( )-l,3-Dienyl-boronate (24) is selectively obtained in the presence of a chelating bisphosphine such as dppf and dppe. On the other hand, a combination of Pdjldba), with Ph2PC6p5 (1-2 equiv. per palladium) yields allenylboronate (23) as the major product. Thus, a double coordination of two C-C unsaturated bonds of enyne to a coordinate unsaturated catalyst affords 1,4-addition product On the other hand, a monocoordination of an acetylenic triple bond to a rhodium(I)/bisphosphine complex leads to 24. Thus, asymmetric hydroboration of l-buten-3-yne giving (R)-allenyl-boronate with 61% ee is carried out by using a chiral monophosphine (S)-(-)-MeO-MOP (MeO-MOP=2-diphenylphosphino-2 -methoxy-l,l -binaphthyl) [52]. 

Fig. 5.5.15 Spatially resolved 13C DEPT spectra recorded for the competitive etherification and hydration reactions of 2-methyl-2-butene (2M2B) to 2-methoxy-2-methylbutane (tert-amyl methyl ether, TAME) and 2-methyl-butan-2-ol (tert-amyl alcohol, TAOH), respectively. The molar composition of the feed was in the ratio 2 10 1 for 2M2B methanol water. The...

In view of the results obtained for attack of acetone singlets on 1-methoxy-butene to yield singlet biradicals (partial loss of stereochemistry due to bond rotation in the biradical), acetone attack on dicyanoethylene to yield oxetane stereospecifically via a similar biradical intermediate is difficult to envision. Thus a new mechanism must be developed to account for these results. 

A mixture of sodamide, bromoanisole, and l-methoxy-2-methyl-l-(trimethylsilyl-oxy)-l-butene were reacted at room temperature at a 50 millimolar scale. After some two horns, with slight emission of ammonia, the reaction suddenly became exothermic, with violent gas emission and on one occasion a fire. This was a modest scale-up of a literature procedure for synthesis of 2-alky lbenzoic acids, via a benzyne intermediate. It is advised that this reaction be employed only on smaller scale, with safety precautions. The reaction must pass through a benzocyclobutane intermediate, this, or another, high energy species might accumulate and then decompose. 

Commereuc and Chauvin studied the effect of ligands on the reaction of ethanol (43). When bis(diphenylphosphino)-1,2-ethane (39) was used with PdCl2 and sodium phenoxide, 1 1 products [l-methoxy-2-butene (40) and 3-methoxy-l-butene (41)] and a 1 2 product [8-methoxy-l,6-octadiene (36)] were obtained in equal amounts. Nickel-PEt3 catalyst gave a mixture of the 1 2 and 1 1 telomers ... 

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