4-Penten-l-ol acetate

Pentadiene has been prepared by the interaction of allyl bromide and vinyl bromide in the presence of magnesium and by the pyrolysis of 1,5-pentanediol diacetate or 4-penten-l-ol acetate. The present procedure is essentially that of Shoemaker and Boord with some modifications. ... 

The residue from the first distillation is a mixture of acetic acid, 4-penten-l-ol acetate, and 1,5-pentanediol diacetate. Another 15-35 g. (6-15%) of 1,4-pentadiene can be obtained by passing the residue through the pyrolysis tube under the conditions described above. 

The bromide could be prepared from 3-phenyl-l-propanol ( 59/kg). The unsaturated aldehyde O can be made by oxidation (Cr03.py) of 4-penten-l-ol ( 41.80/10 g). A cheaper way is to make ethyl 4-pentenoate from ethyl acetate ( 15/gal) and allyl bromide ( 19/100 g) and reduce it to the aldehyde O with DIB AH ( 19/ 0.1 mol). 

The scope of this approach was widened by the observation of excellent enantioselectivities in intermolecular [2 +2]-photocycloaddition reactions with various alkenes [62,71]. In the presence of an excess amount of alkene, 4-me-thoxy-2-quinolone (57) was converted with high chemo- and regioselectivity to the exo and endo cyclobutanes 59 and 60. With 4-penten-l-ol (58a), allyl acetate (58b), methyl acrylate (58c), and vinyl acetate (58d), the exo diastereomers 59a-d were formed with high simple diastereoselectivity and in high yields (80-89%). Under optimized irradiation conditions (2.4 eq. of host 44 or entA4, — 60°C), high enantiomeric excesses were achieved in all instances, as depicted in Scheme 22. These enantiomeric excesses are unprecedented for an intermolecular photochemical reaction. 

Reaction of 4-penten-l-ol with mercuric acetate followed by reduction with sodium borohydride yields 2-methyl-oxolane. Write the strucmre of the intermediate and explain the formation of this ether. 

The aroma compounds of olive oil have recently been reviewed by Kiritsakis (60). The most abundant aroma compounds in virgin olive oil are C-6 aliphatic compounds, frani-2-hexenal, frani-2-hexen-l-ol, hexan-l-ol, cw-3-hexen-l-ol, di-2-penten-l-ol, c/i-3-hexenal, hexyl acetate, and hexanal, accounting for about 80% of total volatile compounds with the prominence of tran -2-hexenal (61-64). These C-6 compounds provide the green perception and unique aroma of olive oil. Recently, 2,4-dimethylfuran has been found in olive oil with unpleasant sensory quality (65). As a result, the ratio of trani-2-hexenal/2,4-dimethylfuran has been proposed as a quality marker for olive oil and the ratio value of less than 1.5 indicates lower quality olive oil (65). 

Apart from the technical route described to p-apo-8 -carotenal, readily available vitamin A alcohol (Cjo) has served as an intermediate in the form of the phosphonium salt by reaction with the monodiethyl acetal of a Cio dial (ref. 54). The required Cjo monodiethylacetal was obtained (ref.5, p409) by the reaction of the mono aldehyde-protected derivative, the enol ether of methylmalonaldehyde, (C4) with the acetylenic Grignard reagent from trans 3-methyl-2-penten-4-yn-l-ol (C ) followed by acidic dehydration and partial reduction with Lindlar catalyst to give firstly 8-hydroxy-2,6-dimethylocta-2, 4,6-triene-l-al (Cio). Protection of the hydroxyl group by acetylation in pyridine solution with acetyl chloride and formation of the diethyl acetal with ethyl orthoformate followed by hydrolysis of the acetyl group and oxidation afforded the final CIO aldehyde component (D)shown in Scheme 15a. 

We initially tested Candida antarctica lipase using imidazolium salt as solvent because CAL was found to be the best enzyme to resolve our model substrate 5-phenyl-l-penten-3-ol (la) the acylation rate was strongly dependent on the anionic part of the solvents. The best results were recorded when [bmim][BF4] was employed as the solvent, and the reaction rate was nearly equal to that of the reference reaction in diisopropyl ether. The second choice of solvent was [bmim][PFg]. On the contrary, a significant drop in the reaction rate was obtained when the reaction was carried out in TFA salt or OTf salt. From these results, we concluded that BF4 salt and PFg salt were suitable solvents for the present lipase-catalyzed reaction. Acylation of la was accomplished by these four enzymes Candida antarctica lipase, lipase QL from Alcaligenes, Lipase PS from Burkholderia cepacia and Candida rugosa lipase. In contrast, no reaction took place when PPL or PLE was used as catalyst in this solvent system. These results were established in March 2000 but we encountered a serious problem in that the results were significantly dependent on the lot of the ILs that we prepared ourselves. The problem was very serious because sometimes the reaction did not proceed at all. So we attempted to purify the ILs and established a very successful procedure (Fig. 3) the salt was first washed with a mixed solvent of hexane and ethyl acetate (2 1 or 4 1), treated with activated charcoal and passed into activated alumina neutral type I as an acetone solution. It was evaporated and dried under reduced... 

Clausen et al. (2005) found many similarities between odorants emitted from linseed oil as well as from a floor oil made of this linseed oil, concluding that the odorants of the linseed oil are also responsible for the odor of the floor oil. Of the 139 listed perceived odorants only 45 were identified by GC—MS library search and retention characteristics. Important odorants with a high detection frequency were acetaldehyde, propanal, butanal, pentanal, 2-pentenal, hexanal, 2-hexenal, heptanal, 2-heptenal, 2,4-heptadienal, octanal, 2-octenal, nonanal, 2-nonenal, 2-decenal, benzaldehyde, l-penten-3-one, l-penten-3-ol, pentyl oxiran, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid. 

Methyl-l-penten-3-one-l-ol 1 and glacial acetic acid in benzene was added to pyrrolidine to give 2-methyl-l-pen ten-1-[N-pyrrolidinyl]-3-one 2. Compound 2 when treated with oxalyl chloride and methanol was added, 3,5-dimethyl-2-methoxycarbonyl-4-pyrone 3 was produced. Treatment of compound 3 with sodium borohydride in methanol gives 3,5-dimethyl-2-hydroxymethyl-4-pyrone 4. Compound 4 was converted to 3,5-dimethyl-2-hydroxymethyl-4-pyridone 5 by heating compound 4 with aqueous ammonia in a sealed flask. Compound 5 was converted to 4-chloro-2-chloromethyl-3,5-dimethyl pyridine 6 by treatment with phosphorous oxychloride. Treatment of compound 6 with 5-methoxy-2-mer-captobenzimidazole in tetrahydrofuran gave 2-[2-(4-chloro-3,5-dimethyl pyridinyl)methylthio]-5-methoxy benzimidazole 7. When compound 7 was treated with potassium hydroxide in dimethyl sulfoxide containing methanol, 2-[2-(3,5-dimethyl-4-methoxypyridinyl)methylthio]-5-methoxy... 

Reaction with aUyhc alcohols (1, 271 272). The reaction of rran.v-3-penten-2-ol (1) with N, N-dimethylacetamide dimethyl acetal and/or its synthetic equivalent 1 -methoxy-l-dimcthylaminoethylene in refluxing xylene for 17 hr. gives the N,N-dimethylamide of 3-mcthyl-4-trani-hexenoic acid (2) in 80% yield. When the reaction was carried out... 

Propionic 4-(p-Hydroxyphenyl)-2-butanone Isoamyl acetate l-Penten-3-ol... 

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