3- Dimethylallyl alcohol

The biosynthesis of monoterpenes, the major components of peppermint essential oils, can be divided into four stages (Fig. 9.4). Stage 1 includes the formation of isopentenyl diphosphate (IPP) and dimethylallyl alcohol (DMAPP). In plants, two separate pathways are utilized for the synthesis of these universal C5 intermediates, with the cytosolic mevalonate pathway being responsible for the formation of sterols and certain sesquiterpenes, and the plastidial mevalonate-independent pathway being involved in the biosynthesis of isoprene, monoterpenes, certain sesquiterpenes, diterpenes, tetraterpenes, as well as the side chains of chlorophyll and plastoquinone.16 In peppermint oil gland secretory cells, however, the mevalonate pathway is blocked and the biosynthesis of monoterpenoid essential... 

This evidently accounts for the presence of isoprene in the breath.34 Isoprene is also formed by many plants and is released into the atmosphere in large amounts, which contribute to photochemical formation of haze. A Mg2+-dependent enzyme catalyzes the elimination of pyrophosphate.35 Isoprene emissions rise with increasing temperature, and it has been suggested that the isoprene may dissolve in chloroplast membranes and in some way confer increased heat resistance.36 37 Hydrolytic dephosphorylation can lead to dimethylallyl alcohol, which is oxidized in the liver to dimethy-lacrylyl-CoA (Eq. 22-1). 

Dimethylallyl alcohol was epoxidized with better than 90% ee (entry 1) but in low yield when a stoichiometric amount of the Ti-tartrate complex was used. However, when a catalytic amount of the complex was used and an in situ derivatization employed, the p-nitrobenzoate (>98% ee after recrystallization) and / -toluenesulfonate (93% ee) were isolated in yields of 70 and 55%, respectively. 

The rationale that explains the kinetic resolution of the 1-monosubstituted allylic alcohols predicts that a 1,1-disubstituted allylic alcohol will be difficult to epoxidize with the Ti-tartrate catalyst. In practice, the epoxidation of 1,1-dimethylallyl alcohol (88) with a stoichiometric quantity of the Ti-tartrate complex is very slow, and no epoxy alcohol is isolated... 

Terpenoid Synthesis from Isoprene.—Interest continues in new syntheses of iso-prene and its derivatives the dioxan (37) is obtained108 in good yield by the Prins reaction of methylallyl chloride with formaldehyde (cf. Vol. 5, p. 8) free-radical addition of isopropyl alcohol to vinyl acetate yields compound (38) which gives isoprene by acid-catalysed reaction over alumina.109 (Z)-2-Methylbut-2-en-l-ol and dimethylallyl alcohol are readily available from frans-crotyl alcohol.110... 

The diphosphate (44) is also available in 25% yield by regioselective hy-droxylation and diphosphorylation of dimethylallyl alcohol (Scheme 8). ... 

Quinoline and Acridone Alkaloids.—Earlier studies have shown that the quinoline nucleus of skimmianine (38) and dictamnine (37) is derived from anthranilic acid and acetate. Whilst incorporation of mevalonate into dictamnine in Dictamnus albus and into the furanoquinoline alkaloids of Skirnmia japonica could not be demonstrated, positive results have been obtained in Fagara coco. [4- " C]Mevalonic acid, [5- " C]mevalonic acid, and [l- " C]dimethylallyl alcohol were satisfactorily incorporated into skimmianine (38) and the activity was confined essentially to C-2, C-3, and C-3 respectively. 

The biosynthesis is closely related to the already established route to the quinoline system of the furanoquinoline alkaloids such as skimmianine (107) (Scheme 25). Two papers have been published this year on the biosynthesis of (107) but they add nothing new to the earlier work reviewed last year.73 Briefly, the results confirm that (i) C(2) and C(3) of the furan ring of (107) are derived in Fagara coco plants from C(4) and C(5) respectively of mevalonic acid,74 (ii) in the same plant, activity is incorporated specifically at C(3) of the furan from C(l) of dimethylallyl alcohol,75 and (iff) 2,4-dihydroxy[3-14C,15N]quinoline (106) is an efficient and specific precursor of the quinoline system of (107) in Ruta graveolens and is incorporated without randomization.75 Surprisingly, the isomer kokusaginine (108) showed a random incorporation in this experiment. 

Reed found that crystalline prenyltransferase could solvolyze the allylic substrates. This reaction required inorganic pyrophosphate and had a velocity of about 2% of the normal reaction rate [6]. Examination of the allylic product, either dimethylallyl alcohol or geraniol, revealed that C-1 had inverted and the csu-binol oxygen had come from water. Since the normal reaction involves inversion of C-1 and scission of C-O bond, the solvolysis seemed to be mimicking the normal reaction, with H2O replacing the organic portion of isopentenyl pyrophosphate in the catalytic site. This indicates that ionization of the allylic pyrophosphate is the first event, followed by condensation to form a new bond, then a hydrogen elimination from C-2 of the former isopentenyl moiety. Thus, there is an ionization-condensation-elimination sequence of events. 

B.27) (B.27) 2-Buten-l-ol, 3-methyl-, 3-methylhut-2-en-l-ol, 3,3-dimethylallyl alcohol, prenol, prenyl alcohol [556-82-1] FEMA 3647... 

B.34) (B.34) 3-Buten-2-ol, 2-methyl-,2-methylbut-3-en-2-ol, l,l-dimethyl-2-propenol, 1,1-dimethylallyl alcohol, dimethyl vinyl carbinol, 3-hydroxy-3-methyl-l-butene 115-18-4]... 

Allylic alcohols, for example geraniol, 2-methylallyl alcohol, 3,3-dimethylallyl alcohol, 3-buten-2-ol, l-octen-3-ol, and l-hexen-3-ol, are epoxidized with tert-butyl hydroperoxide in the presence of a vanadyl salen oxo-transfer catalyst in supercritical CO2. The metal catalyst was prepared in a simple two-step, Schiff base-type reaction to form the salen ligand, followed by complexation to the vanadyl group. The use of non-toxic supercritical CO2 in the presence of the new epoxidation vanadium catalyst led to yields and diastereoselectivities that were comparable to those resulting from the use of environmentally hazardous solvents such as CH2CI2 [59]. 

Beilstein Handbook Reference) BRN 1633479 2-Buten-1-ol, 8methyl- 3,3-Dimethylallyl alcohol Oimethylallyl alcohol EINECS 209-141-4 FEMA No. 3647 3-Methyl-2-buten-1-ol ... 

All these easy condensations of 2-methylbut-3-ene-2-ol or 3-methylbut-2-enol (y,y-dimethylallyl alcohol) with mono- and dihydric pheniols under very mild acidic conditions do support the biogenetic theory of C-isopentenylation with y,y-dimethylallyl pyrophosphate (ref.1). 

Isomerization of vinylcarbinols to ally lie alcohols. Treatment of a tertiary vinylcarbinol, available by the reaction of a ketone with a vinyhnagnesium halide, with acetic acid-acetic anhydride and a trace of p-toluenesulfonic acid at 20° (cooling) for several hours results in isomerization to the acetate of the isomeric primary allylic alcohol. An example is the preparation of 3,3-dimethylallyl alcohol from 2-methyl-3-butene-2-ol. 

Due to the formation of sterically encumbered 7t-allyl palladium-species, a,a- and y,y-dimethylallyl alcohols failed to react. Enolisable aldehydes were also suitable substrates, and of note, quaternaiy centres eould be accessed via disubstituted aldehydes. 

Dimethylallyl acetate 3,3-Dimethylallyl acetate Y,Y-Dimethylallyl acetate. See Prenyl acetate Dimethylallyl alcohol. See3-Methyl-2-buten-1-ol 1,1-Dimethylallyl alcohol. See 2-Methyl-3-buten-2-ol... 

Dimethylallyl alcohol y.y-Dimethylallyl alcohol. See 3-Methyl-2-buten-1-ol Dimethylaluminum chloride CAS 1184-58-3 EINECS/ELINCS 214-668-8 Synonyms Aluminum, chlorodimethyl- DMAC Classification Metal alkyl organometallic compd. Empirical C2H6AICI Formula (CH3)2AICI... 

CAS 115-18-4 EINECS/ELINCS 204-068-4 Synonyms 1,1-Dimethylallyl alcohol 3-Hydroxy-3-methyl-1-butene Methylbutenol 3-Methyl-1-buten-3-ol Empirical C5H10O Formula CH2 CHC(CH3)20H Properties Oily liq. herbaceous earthy odor m.w. 86.14 dens. 0.824 (20/4 C) b.p. 96-99 C flash pt. 10 C ref. index 1.418 (20 C)... 

Synonyms Dimethylallyl alcohol 3,3-Dimethylallyl alcohol Y,Y-Dimethylallyl alcohol 3-Methyl-2-butene-1-ol 3-Methylbut-2-en-1-ol Prenol Prenyl alcohol Vertenol... 

Hemiterpenes Isoprene, 3,3-dimethylallyl alcohol, isopentenol, isoamyl alcohol... 

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